QString Class Reference

#include <qstring.h>

Inheritance diagram for QString:

Collaboration diagram for QString:

Public Types
enum	SectionFlag {   SectionDefault = 0x00 , SectionSkipEmpty = 0x01 , SectionIncludeLeadingSep = 0x02 , SectionIncludeTrailingSep = 0x04 ,   SectionCaseInsensitiveSeps = 0x08 }
	This enum specifies flags that can be used to affect various aspects of the section() function's behavior with respect to separators and empty fields. More...
enum	NormalizationForm { NormalizationForm_D , NormalizationForm_C , NormalizationForm_KD , NormalizationForm_KC }
	This enum describes the various normalized forms of Unicode text. More...
typedef QStringPrivate	DataPointer
typedef QChar *	iterator
typedef const QChar *	const_iterator
typedef iterator	Iterator
	Qt-style synonym for QString::iterator.
typedef const_iterator	ConstIterator
	\macro QT_RESTRICTED_CAST_FROM_ASCII
typedef std::reverse_iterator< iterator >	reverse_iterator
typedef std::reverse_iterator< const_iterator >	const_reverse_iterator
typedef qsizetype	size_type
typedef qptrdiff	difference_type
typedef const QChar &	const_reference
typedef QChar &	reference
typedef QChar *	pointer
	The QString::pointer typedef provides an STL-style pointer to a QString element (QChar).
typedef const QChar *	const_pointer
	The QString::const_pointer typedef provides an STL-style const pointer to a QString element (QChar).
typedef QChar	value_type

Public Member Functions
constexpr	QString () noexcept
	Constructs a null string.
	QString (const QChar *unicode, qsizetype size=-1)
	Constructs a string initialized with the first size characters of the QChar array unicode.
	QString (QChar c)
	Constructs a string of size 1 containing the character ch.
	QString (qsizetype size, QChar c)
	Constructs a string of the given size with every character set to ch.
	QString (QLatin1StringView latin1)
	Constructs a copy of the Latin-1 string viewed by str.
	QString (QStringView sv)
	QString (const QString &) noexcept
	Constructs a copy of other.
	~QString ()
	Destroys the string.
QString &	operator= (QChar c)
QString &	operator= (const QString &) noexcept
	Assigns other to this string and returns a reference to this string.
QString &	operator= (QLatin1StringView latin1)
	QString (QString &&other) noexcept=default
	Move-constructs a QString instance, making it point at the same object that other was pointing to.
void	swap (QString &other) noexcept
constexpr qsizetype	size () const noexcept
	Returns the number of characters in this string.
constexpr qsizetype	length () const noexcept
	Returns the number of characters in this string.
constexpr bool	isEmpty () const noexcept
	Returns true if the string has no characters; otherwise returns false.
void	resize (qsizetype size)
	Sets the size of the string to size characters.
void	resize (qsizetype size, QChar fillChar)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
void	resizeForOverwrite (qsizetype size)
QString &	fill (QChar c, qsizetype size=-1)
	Sets every character in the string to character ch.
void	truncate (qsizetype pos)
	Truncates the string starting from, and including, the element at index position.
void	chop (qsizetype n)
	Removes n characters from the end of the string.
QString &	slice (qsizetype pos)
QString &	slice (qsizetype pos, qsizetype n)
qsizetype	capacity () const
	Returns the maximum number of characters that can be stored in the string without forcing a reallocation.
void	reserve (qsizetype size)
	Ensures the string has space for at least size characters.
void	squeeze ()
	Releases any memory not required to store the character data.
const QChar *	unicode () const
	Returns a Unicode representation of the string.
QChar *	data ()
	Returns a pointer to the data stored in the QString.
const QChar *	data () const
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
const QChar *	constData () const
	Returns a pointer to the data stored in the QString.
void	detach ()
bool	isDetached () const
bool	isSharedWith (const QString &other) const
void	clear ()
	Clears the contents of the string and makes it null.
const QChar	at (qsizetype i) const
	Returns the character at the given index position in the string.
const QChar	operator[] (qsizetype i) const
QChar &	operator[] (qsizetype i)
	Returns the character at the specified position in the string as a modifiable reference.
QChar	front () const
QChar &	front ()
QChar	back () const
QChar &	back ()
template<typename T, if_integral_non_char< T > = true>
QString	arg (T a, int fieldWidth=0, int base=10, QChar fillChar=u' ') const
template<typename T, if_floating_point< T > = true>
QString	arg (T a, int fieldWidth=0, char format='g', int precision=-1, QChar fillChar=u' ') const
template<typename T, if_string_like< T > = true>
QString	arg (const T &a, int fieldWidth=0, QChar fillChar=u' ') const
	Returns a copy of this string with the lowest-numbered place-marker replaced by string a, i.e., %1, %2, ..., %99.
template<typename... Args>
std::enable_if< sizeof...(Args)>=2 &&std::conjunction_v< is_string_like< Args >... >, QString >::type	arg (Args &&...args) const
static QString static QString	QT_CORE_INLINE_SINCE (6, 8) qsizetype indexOf(QChar c
qsizetype	indexOf (QLatin1StringView s, qsizetype from=0, Qt::CaseSensitivity cs=Qt::CaseSensitive) const
qsizetype	indexOf (const QString &s, qsizetype from=0, Qt::CaseSensitivity cs=Qt::CaseSensitive) const
qsizetype	indexOf (QStringView s, qsizetype from=0, Qt::CaseSensitivity cs=Qt::CaseSensitive) const noexcept
qsizetype	lastIndexOf (QChar c, Qt::CaseSensitivity cs=Qt::CaseSensitive) const noexcept
	QT_CORE_INLINE_SINCE (6, 8) qsizetype lastIndexOf(QChar c
qsizetype	lastIndexOf (QLatin1StringView s, Qt::CaseSensitivity cs=Qt::CaseSensitive) const
qsizetype	lastIndexOf (QLatin1StringView s, qsizetype from, Qt::CaseSensitivity cs=Qt::CaseSensitive) const
qsizetype	lastIndexOf (const QString &s, Qt::CaseSensitivity cs=Qt::CaseSensitive) const
qsizetype	lastIndexOf (const QString &s, qsizetype from, Qt::CaseSensitivity cs=Qt::CaseSensitive) const
qsizetype	lastIndexOf (QStringView s, Qt::CaseSensitivity cs=Qt::CaseSensitive) const noexcept
qsizetype	lastIndexOf (QStringView s, qsizetype from, Qt::CaseSensitivity cs=Qt::CaseSensitive) const noexcept
bool	contains (QChar c, Qt::CaseSensitivity cs=Qt::CaseSensitive) const
bool	contains (const QString &s, Qt::CaseSensitivity cs=Qt::CaseSensitive) const
	Returns true if this string contains an occurrence of the string str; otherwise returns false.
bool	contains (QLatin1StringView s, Qt::CaseSensitivity cs=Qt::CaseSensitive) const
bool	contains (QStringView s, Qt::CaseSensitivity cs=Qt::CaseSensitive) const noexcept
qsizetype	count (QChar c, Qt::CaseSensitivity cs=Qt::CaseSensitive) const
qsizetype	count (const QString &s, Qt::CaseSensitivity cs=Qt::CaseSensitive) const
	Returns the number of (potentially overlapping) occurrences of the string str in this string.
qsizetype	count (QStringView s, Qt::CaseSensitivity cs=Qt::CaseSensitive) const
QString	section (QChar sep, qsizetype start, qsizetype end=-1, SectionFlags flags=SectionDefault) const
	This function returns a section of the string.
QString	section (const QString &in_sep, qsizetype start, qsizetype end=-1, SectionFlags flags=SectionDefault) const
QString	left (qsizetype n) const &
QString	left (qsizetype n) &&
QString	right (qsizetype n) const &
QString	right (qsizetype n) &&
QString	mid (qsizetype position, qsizetype n=-1) const &
QString	mid (qsizetype position, qsizetype n=-1) &&
QString	first (qsizetype n) const &
QString	last (qsizetype n) const &
QString	sliced (qsizetype pos) const &
QString	sliced (qsizetype pos, qsizetype n) const &
QString	chopped (qsizetype n) const &
QString	first (qsizetype n) &&
QString	last (qsizetype n) &&
QString	sliced (qsizetype pos) &&
QString	sliced (qsizetype pos, qsizetype n) &&
QString	chopped (qsizetype n) &&
bool	startsWith (const QString &s, Qt::CaseSensitivity cs=Qt::CaseSensitive) const
	Returns true if the string starts with s; otherwise returns false.
bool	startsWith (QStringView s, Qt::CaseSensitivity cs=Qt::CaseSensitive) const noexcept
bool	startsWith (QLatin1StringView s, Qt::CaseSensitivity cs=Qt::CaseSensitive) const
bool	startsWith (QChar c, Qt::CaseSensitivity cs=Qt::CaseSensitive) const
bool	endsWith (const QString &s, Qt::CaseSensitivity cs=Qt::CaseSensitive) const
	Returns true if the string ends with s; otherwise returns false.
bool	endsWith (QStringView s, Qt::CaseSensitivity cs=Qt::CaseSensitive) const noexcept
bool	endsWith (QLatin1StringView s, Qt::CaseSensitivity cs=Qt::CaseSensitive) const
bool	endsWith (QChar c, Qt::CaseSensitivity cs=Qt::CaseSensitive) const
bool	isUpper () const
	Returns true if the string is uppercase, that is, it's identical to its toUpper() folding.
bool	isLower () const
	Returns true if the string is lowercase, that is, it's identical to its toLower() folding.
QString	leftJustified (qsizetype width, QChar fill=u' ', bool trunc=false) const
	Returns a string of size width that contains this string padded by the fill character.
QString	rightJustified (qsizetype width, QChar fill=u' ', bool trunc=false) const
	Returns a string of size() width that contains the fill character followed by the string.
QString	toLower () const &
QString	toLower () &&
QString	toUpper () const &
QString	toUpper () &&
QString	toCaseFolded () const &
QString	toCaseFolded () &&
QString	trimmed () const &
QString	trimmed () &&
QString	simplified () const &
QString	simplified () &&
QString	toHtmlEscaped () const
QString &	insert (qsizetype i, QChar c)
QString &	insert (qsizetype i, const QChar *uc, qsizetype len)
QString &	insert (qsizetype i, const QString &s)
QString &	insert (qsizetype i, QStringView v)
QString &	insert (qsizetype i, QLatin1StringView s)
QString &	insert (qsizetype i, QUtf8StringView s)
QString &	append (QChar c)
QString &	append (const QChar *uc, qsizetype len)
QString &	append (const QString &s)
	Appends the string str onto the end of this string.
QString &	append (QStringView v)
QString &	append (QLatin1StringView s)
QString &	append (QUtf8StringView s)
QString &	prepend (QChar c)
QString &	prepend (const QChar *uc, qsizetype len)
QString &	prepend (const QString &s)
	Prepends the string str to the beginning of this string and returns a reference to this string.
QString &	prepend (QStringView v)
QString &	prepend (QLatin1StringView s)
QString &	prepend (QUtf8StringView s)
QString &	assign (QAnyStringView s)
QString &	assign (qsizetype n, QChar c)
template<typename InputIterator, if_compatible_iterator< InputIterator > = true>
QString &	assign (InputIterator first, InputIterator last)
QString &	operator+= (QChar c)
QString &	operator+= (const QString &s)
	Appends the string other onto the end of this string and returns a reference to this string.
QString &	operator+= (QStringView v)
QString &	operator+= (QLatin1StringView s)
QString &	operator+= (QUtf8StringView s)
QString &	remove (qsizetype i, qsizetype len)
	Removes n characters from the string, starting at the given position index, and returns a reference to the string.
QString &	remove (QChar c, Qt::CaseSensitivity cs=Qt::CaseSensitive)
	Removes every occurrence of the character ch in this string, and returns a reference to this string.
QString &	remove (QLatin1StringView s, Qt::CaseSensitivity cs=Qt::CaseSensitive)
QString &	remove (const QString &s, Qt::CaseSensitivity cs=Qt::CaseSensitive)
	Removes every occurrence of the given str string in this string, and returns a reference to this string.
QString &	removeAt (qsizetype pos)
QString &	removeFirst ()
QString &	removeLast ()
template<typename Predicate>
QString &	removeIf (Predicate pred)
QString &	replace (qsizetype i, qsizetype len, QChar after)
QString &	replace (qsizetype i, qsizetype len, const QChar *s, qsizetype slen)
QString &	replace (qsizetype i, qsizetype len, const QString &after)
	Replaces n characters beginning at index position with the string after and returns a reference to this string.
QString &	replace (QChar before, QChar after, Qt::CaseSensitivity cs=Qt::CaseSensitive)
QString &	replace (const QChar *before, qsizetype blen, const QChar *after, qsizetype alen, Qt::CaseSensitivity cs=Qt::CaseSensitive)
QString &	replace (QLatin1StringView before, QLatin1StringView after, Qt::CaseSensitivity cs=Qt::CaseSensitive)
QString &	replace (QLatin1StringView before, const QString &after, Qt::CaseSensitivity cs=Qt::CaseSensitive)
QString &	replace (const QString &before, QLatin1StringView after, Qt::CaseSensitivity cs=Qt::CaseSensitive)
QString &	replace (const QString &before, const QString &after, Qt::CaseSensitivity cs=Qt::CaseSensitive)
QString &	replace (QChar c, const QString &after, Qt::CaseSensitivity cs=Qt::CaseSensitive)
QString &	replace (QChar c, QLatin1StringView after, Qt::CaseSensitivity cs=Qt::CaseSensitive)
QStringList	split (const QString &sep, Qt::SplitBehavior behavior=Qt::KeepEmptyParts, Qt::CaseSensitivity cs=Qt::CaseSensitive) const
	Splits the string into substrings wherever sep occurs, and returns the list of those strings.
QStringList	split (QChar sep, Qt::SplitBehavior behavior=Qt::KeepEmptyParts, Qt::CaseSensitivity cs=Qt::CaseSensitive) const
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
QStringList	split (const QRegularExpression &sep, Qt::SplitBehavior behavior=Qt::KeepEmptyParts) const
template<typename Needle, typename... Flags>
auto	tokenize (Needle &&needle, Flags...flags) const &noexcept(noexcept(qTokenize(std::declval< const QString & >(), std::forward< Needle >(needle), flags...))) -> decltype(qTokenize(*this, std::forward< Needle >(needle), flags...))
template<typename Needle, typename... Flags>
auto	tokenize (Needle &&needle, Flags...flags) const &&noexcept(noexcept(qTokenize(std::declval< const QString >(), std::forward< Needle >(needle), flags...))) -> decltype(qTokenize(std::move(*this), std::forward< Needle >(needle), flags...))
template<typename Needle, typename... Flags>
auto	tokenize (Needle &&needle, Flags...flags) &&noexcept(noexcept(qTokenize(std::declval< QString >(), std::forward< Needle >(needle), flags...))) -> decltype(qTokenize(std::move(*this), std::forward< Needle >(needle), flags...))
QString	normalized (NormalizationForm mode, QChar::UnicodeVersion version=QChar::Unicode_Unassigned) const
	Returns the string in the given Unicode normalization mode, according to the given version of the Unicode standard.
QString	repeated (qsizetype times) const
const ushort *	utf16 () const
	Returns the QString as a '\0\'-terminated array of unsigned shorts.
QString	nullTerminated () const &
QString	nullTerminated () &&
QString &	nullTerminate ()
QByteArray	toLatin1 () const &
QByteArray	toLatin1 () &&
QByteArray	toUtf8 () const &
QByteArray	toUtf8 () &&
QByteArray	toLocal8Bit () const &
QByteArray	toLocal8Bit () &&
QList< uint >	toUcs4 () const
qsizetype	toWCharArray (wchar_t *array) const
QString &	setRawData (const QChar *unicode, qsizetype size)
QString &	setUnicode (const QChar *unicode, qsizetype size)
	Resizes the string to size characters and copies unicode into the string.
Q_WEAK_OVERLOAD QString &	setUnicode (const char16_t *utf16, qsizetype size)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
QString &	setUtf16 (const char16_t *utf16, qsizetype size)
Q_WEAK_OVERLOAD QString &	setUtf16 (const ushort *autf16, qsizetype asize)
	\obsolete Use the char16_t overload instead.
int	compare (const QString &s, Qt::CaseSensitivity cs=Qt::CaseSensitive) const noexcept
int	compare (QLatin1StringView other, Qt::CaseSensitivity cs=Qt::CaseSensitive) const noexcept
int	compare (QStringView s, Qt::CaseSensitivity cs=Qt::CaseSensitive) const noexcept
int	compare (QChar ch, Qt::CaseSensitivity cs=Qt::CaseSensitive) const noexcept
int	localeAwareCompare (const QString &s) const
int	localeAwareCompare (QStringView s) const
short	toShort (bool *ok=nullptr, int base=10) const
	Returns the string converted to a short using base base, which is 10 by default and must be between 2 and 36, or 0.
ushort	toUShort (bool *ok=nullptr, int base=10) const
	Returns the string converted to an {unsigned short} using base base, which is 10 by default and must be between 2 and 36, or 0.
int	toInt (bool *ok=nullptr, int base=10) const
	Returns the string converted to an int using base base, which is 10 by default and must be between 2 and 36, or 0.
uint	toUInt (bool *ok=nullptr, int base=10) const
	Returns the string converted to an {unsigned int} using base base, which is 10 by default and must be between 2 and 36, or 0.
long	toLong (bool *ok=nullptr, int base=10) const
	Returns the string converted to a long using base base, which is 10 by default and must be between 2 and 36, or 0.
ulong	toULong (bool *ok=nullptr, int base=10) const
	Returns the string converted to an {unsigned long} using base base, which is 10 by default and must be between 2 and 36, or 0.
qlonglong	toLongLong (bool *ok=nullptr, int base=10) const
	Returns the string converted to a {long long} using base base, which is 10 by default and must be between 2 and 36, or 0.
qulonglong	toULongLong (bool *ok=nullptr, int base=10) const
	Returns the string converted to an {unsigned long long} using base base, which is 10 by default and must be between 2 and 36, or 0.
float	toFloat (bool *ok=nullptr) const
	Returns the string converted to a float value.
double	toDouble (bool *ok=nullptr) const
	Returns the string converted to a double value.
QString &	setNum (short, int base=10)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
QString &	setNum (ushort, int base=10)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
QString &	setNum (int, int base=10)
	Sets the string to the printed value of n in the specified base, and returns a reference to the string.
QString &	setNum (uint, int base=10)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
QString &	setNum (long, int base=10)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
QString &	setNum (ulong, int base=10)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
QString &	setNum (qlonglong, int base=10)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
QString &	setNum (qulonglong, int base=10)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
QString &	setNum (float, char format='g', int precision=6)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.Sets the string to the printed value of n, formatted according to the given format and precision, and returns a reference to the string.
QString &	setNum (double, char format='g', int precision=6)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.Sets the string to the printed value of n, formatted according to the given format and precision, and returns a reference to the string.
QT_ASCII_CAST_WARN	QString (const char *ch)
	Constructs a string initialized with the 8-bit string str.
QT_ASCII_CAST_WARN	QString (const QByteArray &a)
	Constructs a string initialized with the byte array ba.
QT_ASCII_CAST_WARN QString &	operator= (const char *ch)
QT_ASCII_CAST_WARN QString &	operator= (const QByteArray &a)
QT_ASCII_CAST_WARN QString &	prepend (const char *s)
QT_ASCII_CAST_WARN QString &	prepend (const QByteArray &s)
QT_ASCII_CAST_WARN QString &	append (const char *s)
QT_ASCII_CAST_WARN QString &	append (const QByteArray &s)
QT_ASCII_CAST_WARN QString &	insert (qsizetype i, const char *s)
QT_ASCII_CAST_WARN QString &	insert (qsizetype i, const QByteArray &s)
QT_ASCII_CAST_WARN QString &	operator+= (const char *s)
QT_ASCII_CAST_WARN QString &	operator+= (const QByteArray &s)
iterator	begin ()
	Returns an \l{STL-style iterators}{STL-style iterator} pointing to the first character in the string.
const_iterator	begin () const
const_iterator	cbegin () const
const_iterator	constBegin () const
	Returns a const \l{STL-style iterators}{STL-style iterator} pointing to the first character in the string.
iterator	end ()
	Returns an \l{STL-style iterators}{STL-style iterator} pointing just after the last character in the string.
const_iterator	end () const
const_iterator	cend () const
const_iterator	constEnd () const
	Returns a const \l{STL-style iterators}{STL-style iterator} pointing just after the last character in the string.
reverse_iterator	rbegin ()
reverse_iterator	rend ()
const_reverse_iterator	rbegin () const
const_reverse_iterator	rend () const
const_reverse_iterator	crbegin () const
const_reverse_iterator	crend () const
void	push_back (QChar c)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.Appends the given ch character onto the end of this string.
void	push_back (const QString &s)
	This function is provided for STL compatibility, appending the given other string onto the end of this string.
void	push_front (QChar c)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.Prepends the given ch character to the beginning of this string.
void	push_front (const QString &s)
	This function is provided for STL compatibility, prepending the given other string to the beginning of this string.
void	shrink_to_fit ()
iterator	erase (const_iterator first, const_iterator last)
iterator	erase (const_iterator it)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
constexpr qsizetype	max_size () const noexcept
std::string	toStdString () const
	Returns a std::string object with the data contained in this QString.
std::wstring	toStdWString () const
	Returns a std::wstring object with the data contained in this QString.
std::u16string	toStdU16String () const
std::u32string	toStdU32String () const
Q_IMPLICIT	operator std::u16string_view () const noexcept
constexpr bool	isNull () const
	Returns true if this string is null; otherwise returns false.
bool	isRightToLeft () const
	Returns true if the string is read right to left.
bool	isValidUtf16 () const noexcept
	QString (qsizetype size, Qt::Initialization)
	QString (DataPointer &&dd)
DataPointer &	data_ptr ()
const DataPointer &	data_ptr () const

Static Public Member Functions
static constexpr qsizetype	maxSize () noexcept
static QString	vasprintf (const char *format, va_list ap) Q_ATTRIBUTE_FORMAT_PRINTF(1
static QString static QString	asprintf (const char *format,...) Q_ATTRIBUTE_FORMAT_PRINTF(1
static QString	fromLatin1 (QByteArrayView ba)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
static Q_WEAK_OVERLOAD QString	fromLatin1 (const QByteArray &ba)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
static QString	fromLatin1 (const char *str, qsizetype size)
	Returns a QString initialized with the first size characters of the Latin-1 string str.
static QString	fromUtf8 (QByteArrayView utf8)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
static Q_WEAK_OVERLOAD QString	fromUtf8 (const QByteArray &ba)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
static QString	fromUtf8 (const char *utf8, qsizetype size)
	Returns a QString initialized with the first size bytes of the UTF-8 string str.
static QString	fromLocal8Bit (QByteArrayView ba)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
static Q_WEAK_OVERLOAD QString	fromLocal8Bit (const QByteArray &ba)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
static QString	fromLocal8Bit (const char *str, qsizetype size)
	Returns a QString initialized with the first size characters of the 8-bit string str.
static QString	fromUtf16 (const char16_t *, qsizetype size=-1)
static QString	fromUcs4 (const char32_t *, qsizetype size=-1)
static QString	fromRawData (const char16_t *unicode, qsizetype size)
static QString	fromRawData (const QChar *, qsizetype size)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
static QString	fromWCharArray (const wchar_t *string, qsizetype size=-1)
static int	compare (const QString &s1, const QString &s2, Qt::CaseSensitivity cs=Qt::CaseSensitive) noexcept
static int	compare (const QString &s1, QLatin1StringView s2, Qt::CaseSensitivity cs=Qt::CaseSensitive) noexcept
static int	compare (QLatin1StringView s1, const QString &s2, Qt::CaseSensitivity cs=Qt::CaseSensitive) noexcept
static int	compare (const QString &s1, QStringView s2, Qt::CaseSensitivity cs=Qt::CaseSensitive) noexcept
static int	compare (QStringView s1, const QString &s2, Qt::CaseSensitivity cs=Qt::CaseSensitive) noexcept
static int	localeAwareCompare (const QString &s1, const QString &s2)
	Compares s1 with s2 and returns an integer less than, equal to, or greater than zero if s1 is less than, equal to, or greater than s2.
static int	localeAwareCompare (QStringView s1, QStringView s2)
static QString	number (int, int base=10)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
static QString	number (uint, int base=10)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
static QString	number (long, int base=10)
	Returns a string equivalent of the number n according to the specified base.
static QString	number (ulong, int base=10)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
static QString	number (qlonglong, int base=10)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
static QString	number (qulonglong, int base=10)
	This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.
static QString	number (double, char format='g', int precision=6)
	Returns a string representing the floating-point number n.
static QString	fromStdString (const std::string &s)
static QString	fromStdWString (const std::wstring &s)
	Returns a copy of the str string.
static QString	fromStdU16String (const std::u16string &s)
static QString	fromStdU32String (const std::u32string &s)

Public Attributes
static QString static QString qsizetype	from = 0
static QString static QString qsizetype Qt::CaseSensitivity	cs = Qt::CaseSensitive) const
qsizetype	from
qsizetype Qt::CaseSensitivity	cs = Qt::CaseSensitive) const

Friends
class	::tst_QString
class	QStringView
class	QByteArray
struct	QAbstractConcatenable
bool	comparesEqual (const QString &s1, const QString &s2) noexcept
Qt::strong_ordering	compareThreeWay (const QString &s1, const QString &s2) noexcept
Q_WEAK_OVERLOAD friend bool	comparesEqual (const QString &s1, QUtf8StringView s2) noexcept
Q_WEAK_OVERLOAD friend Qt::strong_ordering	compareThreeWay (const QString &s1, QUtf8StringView s2) noexcept
bool	comparesEqual (const QString &s1, QLatin1StringView s2) noexcept
Qt::strong_ordering	compareThreeWay (const QString &s1, QLatin1StringView s2) noexcept
bool	comparesEqual (const QString &s1, std::nullptr_t) noexcept
Qt::strong_ordering	compareThreeWay (const QString &s1, std::nullptr_t) noexcept
bool	comparesEqual (const QString &s1, const char16_t *s2) noexcept
Qt::strong_ordering	compareThreeWay (const QString &s1, const char16_t *s2) noexcept
bool	comparesEqual (const QString &lhs, QChar rhs) noexcept
Qt::strong_ordering	compareThreeWay (const QString &lhs, QChar rhs) noexcept
bool	comparesEqual (const QString &lhs, QByteArrayView rhs) noexcept
Qt::strong_ordering	compareThreeWay (const QString &lhs, QByteArrayView rhs) noexcept
bool	comparesEqual (const QString &lhs, const QByteArray &rhs) noexcept
Qt::strong_ordering	compareThreeWay (const QString &lhs, const QByteArray &rhs) noexcept
bool	comparesEqual (const QString &lhs, const char *rhs) noexcept
Qt::strong_ordering	compareThreeWay (const QString &lhs, const char *rhs) noexcept
template<typename T>
qsizetype	erase (QString &s, const T &t)
template<typename Predicate>
qsizetype	erase_if (QString &s, Predicate pred)

Related Symbols
(Note that these are not member symbols.)
QString	operator+ (QString &&s1, const QString &s2)
	Returns a string which is the result of concatenating s1 and s2.
QString	operator+ (const QString &s1, const char *s2)
	Returns a string which is the result of concatenating s1 and s2 (s2 is converted to Unicode using the QString::fromUtf8() function).
QString	operator+ (const char *s1, const QString &s2)
	Returns a string which is the result of concatenating s1 and s2 (s1 is converted to Unicode using the QString::fromUtf8() function).
QString	operator+ (const QString &lhs, QStringView rhs)
QDataStream &	operator<< (QDataStream &stream, const QString &string)
	Writes the given string to the specified stream.
QDataStream &	operator>> (QDataStream &stream, QString &string)
	Reads a string from the specified stream into the given string.
	operator""_s (const char16_t *str, size_t size)
	\macro QStringLiteral(str)

Detailed Description

Definition at line 140 of file qstring.h.

Member Typedef Documentation

const_iterator

typedef const QChar* QString::const_iterator

See also

QString::iterator

Definition at line 1048 of file qstring.h.

const_pointer

typedef const QChar* QString::const_pointer

The QString::const_pointer typedef provides an STL-style const pointer to a QString element (QChar).

Definition at line 1074 of file qstring.h.

const_reference

typedef const QChar& QString::const_reference

Definition at line 1071 of file qstring.h.

const_reverse_iterator

typedef std::reverse_iterator<const_iterator> QString::const_reverse_iterator

Since

5.6

See also

QString::reverse_iterator, QString::const_iterator

Definition at line 1052 of file qstring.h.

ConstIterator

typedef const_iterator QString::ConstIterator

\macro QT_RESTRICTED_CAST_FROM_ASCII

Disables most automatic conversions from source literals and 8-bit data to unicode QStrings, but allows the use of the {QChar(char)} and {QString(const char (&ch)[N]} constructors, and the {QString::operator=(const char (&ch)[N])} assignment operator. This gives most of the type-safety benefits of \l QT_NO_CAST_FROM_ASCII but does not require user code to wrap character and string literals with QLatin1Char, QLatin1StringView or similar.

Using this macro together with source strings outside the 7-bit range, non-literals, or literals with embedded NUL characters is undefined.

See also

QT_NO_CAST_FROM_ASCII, QT_NO_CAST_TO_ASCII

\macro QT_NO_CAST_FROM_ASCII

Disables automatic conversions from 8-bit strings ({char *}) to Unicode QStrings, as well as from 8-bit {char} types ({char} and {unsigned char}) to QChar.

See also

QT_NO_CAST_TO_ASCII, QT_RESTRICTED_CAST_FROM_ASCII, QT_NO_CAST_FROM_BYTEARRAY

\macro QT_NO_CAST_TO_ASCII

Disables automatic conversion from QString to 8-bit strings ({char *}).

See also

QT_NO_CAST_FROM_ASCII, QT_RESTRICTED_CAST_FROM_ASCII, QT_NO_CAST_FROM_BYTEARRAY

\macro QT_ASCII_CAST_WARNINGS

This macro can be defined to force a warning whenever a function is called that automatically converts between unicode and 8-bit encodings.

Note: This only works for compilers that support warnings for deprecated API.

See also

QT_NO_CAST_TO_ASCII, QT_NO_CAST_FROM_ASCII, QT_RESTRICTED_CAST_FROM_ASCII

\class QString
\inmodule QtCore
\reentrant

\brief The QString class provides a Unicode character string.

\ingroup tools
\ingroup shared
\ingroup string-processing

\compares strong
\compareswith strong QChar QLatin1StringView {const char16_t *} \
              QStringView QUtf8StringView
\endcompareswith
\compareswith strong QByteArray QByteArrayView {const char *}
When comparing with byte arrays, their content is interpreted as UTF-8.
\endcompareswith

QString stores a string of 16-bit \l{QChar}s, where each QChar
corresponds to one UTF-16 code unit. (Unicode characters
with code values above 65535 are stored using surrogate pairs,
that is, two consecutive \l{QChar}s.)

\l{Unicode} is an international standard that supports most of the
writing systems in use today. It is a superset of US-ASCII (ANSI
X3.4-1986) and Latin-1 (ISO 8859-1), and all the US-ASCII/Latin-1
characters are available at the same code positions.

Behind the scenes, QString uses \l{implicit sharing}
(copy-on-write) to reduce memory usage and to avoid the needless
copying of data. This also helps reduce the inherent overhead of
storing 16-bit characters instead of 8-bit characters.

In addition to QString, Qt also provides the QByteArray class to
store raw bytes and traditional 8-bit '\\0'-terminated strings.
For most purposes, QString is the class you want to use. It is
used throughout the Qt API, and the Unicode support ensures that
your applications are easy to translate if you want to expand
your application's market at some point. Two prominent cases
where QByteArray is appropriate are when you need to store raw
binary data, and when memory conservation is critical (like in
embedded systems).

\section1 Initializing a string

One way to initialize a QString is to pass a \c{const char

} to its constructor. For example, the following code creates a QString of size 5 containing the data "Hello":

QString converts the {const char *} data into Unicode using the fromUtf8() function.

In all of the QString functions that take {const char *} parameters, the {const char *} is interpreted as a classic C-style {'\0'}-terminated string. Except where the function's name overtly indicates some other encoding, such {const char *} parameters are assumed to be encoded in UTF-8.

You can also provide string data as an array of \l{QChar}s:

QString makes a deep copy of the QChar data, so you can modify it later without experiencing side effects. You can avoid taking a deep copy of the character data by using QStringView or QString::fromRawData() instead.

Another approach is to set the size of the string using resize() and to initialize the data character per character. QString uses 0-based indexes, just like C++ arrays. To access the character at a particular index position, you can use \l operator[](). On non-{const} strings, \l operator[]() returns a reference to a character that can be used on the left side of an assignment. For example:

For read-only access, an alternative syntax is to use the at() function:

The at() function can be faster than \l operator[]() because it never causes a \l{deep copy} to occur. Alternatively, use the first(), last(), or sliced() functions to extract several characters at a time.

A QString can embed '\0' characters (QChar::Null). The size() function always returns the size of the whole string, including embedded '\0' characters.

After a call to the resize() function, newly allocated characters have undefined values. To set all the characters in the string to a particular value, use the fill() function.

QString provides dozens of overloads designed to simplify string usage. For example, if you want to compare a QString with a string literal, you can write code like this and it will work as expected:

You can also pass string literals to functions that take QStrings as arguments, invoking the QString(const char *) constructor. Similarly, you can pass a QString to a function that takes a {const char *} argument using the \l qPrintable() macro, which returns the given QString as a {const char *}. This is equivalent to calling <QString>.toLocal8Bit().constData().

QString provides the following basic functions for modifying the character data: append(), prepend(), insert(), replace(), and remove(). For example:

    QString str = "and";
    str.prepend("rock ");     // str == "rock and"
    str.append(" roll");        // str == "rock and roll"
    str.replace(5, 3, "&");   // str == "rock & roll"

In the above example, the replace() function's first two arguments are the position from which to start replacing and the number of characters that should be replaced.

When data-modifying functions increase the size of the string, QString may reallocate the memory in which it holds its data. When this happens, QString expands by more than it immediately needs so as to have space for further expansion without reallocation until the size of the string has significantly increased.

The insert(), remove(), and, when replacing a sub-string with one of different size, replace() functions can be slow (\l{linear time}) for large strings because they require moving many characters in the string by at least one position in memory.

If you are building a QString gradually and know in advance approximately how many characters the QString will contain, you can call reserve(), asking QString to preallocate a certain amount of memory. You can also call capacity() to find out how much memory the QString actually has allocated.

QString provides \l{STL-style iterators} (QString::const_iterator and QString::iterator). In practice, iterators are handy when working with generic algorithms provided by the C++ standard library.

Note

Iterators over a QString, and references to individual characters within one, cannot be relied on to remain valid when any non-{const} method of the QString is called. Accessing such an iterator or reference after the call to a non-{const} method leads to undefined behavior. When stability for iterator-like functionality is required, you should use indexes instead of iterators, as they are not tied to QString's internal state and thus do not get invalidated.

Due to \l{implicit sharing}, the first non-{const} operator or function used on a given QString may cause it to internally perform a deep copy of its data. This invalidates all iterators over the string and references to individual characters within it. Do not call non-const functions while keeping iterators. Accessing an iterator or reference after it has been invalidated leads to undefined behavior. See the \l{Implicit sharing iterator problem} section for more information.

A frequent requirement is to remove or simplify the spacing between visible characters in a string. The characters that make up that spacing are those for which \l {QChar::}{isSpace()} returns true, such as the simple space {' '}, the horizontal tab {'\t'} and the newline {'\n'}. To obtain a copy of a string leaving out any spacing from its start and end, use \l trimmed(). To also replace each sequence of spacing characters within the string with a simple space, {' '}, use \l simplified().

If you want to find all occurrences of a particular character or substring in a QString, use the indexOf() or lastIndexOf() functions.The former searches forward, the latter searches backward. Either can be told an index position from which to start their search. Each returns the index position of the character or substring if they find it; otherwise, they return -1. For example, here is a typical loop that finds all occurrences of a particular substring:

    QString str = "We must be <b>bold</b>, very <b>bold</b>";
    qsizetype j = 0;
 
    while ((j = str.indexOf("<b>", j)) != -1) {
        qDebug() << "Found <b> tag at index position" << j;
        ++j;
    }

QString provides many functions for converting numbers into strings and strings into numbers. See the arg() functions, the setNum() functions, the number() static functions, and the toInt(), toDouble(), and similar functions.

To get an uppercase or lowercase version of a string, use toUpper() or toLower().

Lists of strings are handled by the QStringList class. You can split a string into a list of strings using the split() function, and join a list of strings into a single string with an optional separator using QStringList::join(). You can obtain a filtered list from a string list by selecting the entries in it that contain a particular substring or match a particular QRegularExpression. See QStringList::filter() for details.

To see if a QString starts or ends with a particular substring, use startsWith() or endsWith(). To check whether a QString contains a specific character or substring, use the contains() function. To find out how many times a particular character or substring occurs in a string, use count().

To obtain a pointer to the actual character data, call data() or constData(). These functions return a pointer to the beginning of the QChar data. The pointer is guaranteed to remain valid until a non-{const} function is called on the QString.

QStrings can be compared using overloaded operators such as \l operator<(), \l operator<=(), \l operator==(), \l operator>=(), and so on. The comparison is based exclusively on the lexicographical order of the two strings, seen as sequences of UTF-16 code units. It is very fast but is not what a human would expect; the QString::localeAwareCompare() function is usually a better choice for sorting user-interface strings, when such a comparison is available.

When Qt is linked with the ICU library (which it usually is), its locale-aware sorting is used. Otherwise, platform-specific solutions are used: \list

• On Windows, localeAwareCompare() uses the current user locale, as set in the \uicontrol{regional} and \uicontrol{language} options portion of \uicontrol{Control Panel}.
• On \macos and iOS, \l localeAwareCompare() compares according to the \uicontrol{Order for sorted lists} setting in the \uicontrol{International preferences} panel.
• On other Unix-like systems, the comparison falls back to the system library's strcoll(). \endlist

QString provides the following functions that return a {const char *} version of the string as QByteArray: toUtf8(), toLatin1(), and toLocal8Bit().

\list

• toLatin1() returns a Latin-1 (ISO 8859-1) encoded 8-bit string.
• toUtf8() returns a UTF-8 encoded 8-bit string. UTF-8 is a superset of US-ASCII (ANSI X3.4-1986) that supports the entire Unicode character set through multibyte sequences.
• toLocal8Bit() returns an 8-bit string using the system's local encoding. This is the same as toUtf8() on Unix systems. \endlist

To convert from one of these encodings, QString provides fromLatin1(), fromUtf8(), and fromLocal8Bit(). Other encodings are supported through the QStringEncoder and QStringDecoder classes.

As mentioned above, QString provides a lot of functions and operators that make it easy to interoperate with {const char *} strings. But this functionality is a double-edged sword: It makes QString more convenient to use if all strings are US-ASCII or Latin-1, but there is always the risk that an implicit conversion from or to {const char *} is done using the wrong 8-bit encoding. To minimize these risks, you can turn off these implicit conversions by defining some of the following preprocessor symbols:

\list

• \l QT_NO_CAST_FROM_ASCII disables automatic conversions from C string literals and pointers to Unicode.
• \l QT_RESTRICTED_CAST_FROM_ASCII allows automatic conversions from C characters and character arrays but disables automatic conversions from character pointers to Unicode.
• \l QT_NO_CAST_TO_ASCII disables automatic conversion from QString to C strings. \endlist

You then need to explicitly call fromUtf8(), fromLatin1(), or fromLocal8Bit() to construct a QString from an 8-bit string, or use the lightweight QLatin1StringView class. For example:

QString url = "https://www.unicode.org/"_L1;

Similarly, you must call toLatin1(), toUtf8(), or toLocal8Bit() explicitly to convert the QString to an 8-bit string.

\table 100 % \header

• Note for C Programmers

\row

• Due to C++'s type system and the fact that QString is \l{implicitly shared}, QStrings may be treated like {int}s or other basic types. For example:

QString Widget::boolToString(bool b)
{
    QString result;
    if (b)
        result = "True";
    else
        result = "False";
    return result;
}

The result variable is a normal variable allocated on the stack. When return is called, and because we're returning by value, the copy constructor is called and a copy of the string is returned. No actual copying takes place thanks to the implicit sharing.

\endtable

For historical reasons, QString distinguishes between null and empty strings. A null string is a string that is initialized using QString's default constructor or by passing \nullptr to the constructor. An empty string is any string with size 0. A null string is always empty, but an empty string isn't necessarily null:

    QString().isNull();               // returns true
    QString().isEmpty();              // returns true
 
    QString("").isNull();             // returns false
    QString("").isEmpty();            // returns true
 
    QString("abc").isNull();          // returns false
    QString("abc").isEmpty();         // returns false

All functions except isNull() treat null strings the same as empty strings. For example, toUtf8().constData() returns a valid pointer (not \nullptr) to a '\0' character for a null string. We recommend that you always use the isEmpty() function and avoid isNull().

When a QString::arg() {''} format specifier includes the {'L'} locale qualifier, and the base is ten (its default), the default locale is used. This can be set using \l{QLocale::setDefault()}. For more refined control of localized string representations of numbers, see QLocale::toString(). All other number formatting done by QString follows the C locale's representation of numbers.

When QString::arg() applies left-padding to numbers, the fill character {'0'} is treated specially. If the number is negative, its minus sign appears before the zero-padding. If the field is localized, the locale-appropriate zero character is used in place of {'0'}. For floating-point numbers, this special treatment only applies if the number is finite.

In member functions (for example, arg() and number()) that format floating-point numbers (float or double) as strings, the representation used can be controlled by a choice of format and precision, whose meanings are as for \l {QLocale::toString(double, char, int)}.

If the selected format includes an exponent, localized forms follow the locale's convention on digits in the exponent. For non-localized formatting, the exponent shows its sign and includes at least two digits, left-padding with zero if needed.

Many strings are known at compile time. The QString constructor from C++ string literals will copy the contents of the string, treating the contents as UTF-8. This requires memory allocation and re-encoding string data, operations that will happen at runtime. If the string data is known at compile time, you can use the QStringLiteral macro or similarly {operator""_s} to create QString's payload at compile time instead.

Using the QString {'+'} operator, it is easy to construct a complex string from multiple substrings. You will often write code like this:

    QString foo;
    QString type = "long";
 
    foo = "vector<"_L1 + type + ">::iterator"_L1;
 
    if (foo.startsWith("(" + type + ") 0x"))
        ...

There is nothing wrong with either of these string constructions, but there are a few hidden inefficiencies:

First, repeated use of the {'+'} operator may lead to multiple memory allocations. When concatenating {n} substrings, where {n > 2}, there can be as many as {n - 1} calls to the memory allocator.

These allocations can be optimized by an internal class {QStringBuilder}. This class is marked internal and does not appear in the documentation, because you aren't meant to instantiate it in your code. Its use will be automatic, as described below.

{QStringBuilder} uses expression templates and reimplements the {''} operator so that when you use {''} for string concatenation instead of {'+'}, multiple substring concatenations will be postponed until the final result is about to be assigned to a QString. At this point, the amount of memory required for the final result is known. The memory allocator is then called {once} to get the required space, and the substrings are copied into it one by one.

Additional efficiency is gained by inlining and reducing reference counting (the QString created from a {QStringBuilder} has a ref count of 1, whereas QString::append() needs an extra test).

There are two ways you can access this improved method of string construction. The straightforward way is to include {QStringBuilder} wherever you want to use it and use the {''} operator instead of {'+'} when concatenating strings:

    #include <QStringBuilder>
 
    QString hello("hello");
    QStringView el = QStringView{ hello }.mid(2, 3);
    QLatin1StringView world("world");
    QString message =  hello % el % world % QChar('!');

A more global approach, which is more convenient but not entirely source-compatible, is to define QT_USE_QSTRINGBUILDER (by adding it to the compiler flags) at build time. This will make concatenating strings with {'+'} work the same way as {QStringBuilder's} {''}.

Note

Using automatic type deduction (for example, by using the auto keyword) with the result of string concatenation when QStringBuilder is enabled will show that the concatenation is indeed an object of a QStringBuilder specialization:

    QString str("QStringBuilder");
 
    // "s" type is deduced as QStringBuilder<...>
    auto s = "Like hot glue, " % str % " concatenates strings";
 
    // Similarly the return type of this lambda is deduced as QStringBuilder<...>
    auto concatenateStr = []() {
        return "Like hot glue, " % str % " concatenates strings";
    };

This does not cause any harm, as QStringBuilder will implicitly convert to QString when required. If this is undesirable, then one should specify the necessary types instead of having the compiler deduce them:

    QString s = "Like hot glue, " % str % " concatenates strings";
 
    // With a lambda, specify a trailing return type:
    auto concatenateStr = []() -> QString {
        return "Like hot glue, " % str % " concatenates strings";
    };

The maximum size of QString depends on the architecture. Most 64-bit systems can allocate more than 2 GB of memory, with a typical limit of 2^63 bytes. The actual value also depends on the overhead required for managing the data block. As a result, you can expect a maximum size of 2 GB minus overhead on 32-bit platforms and 2^63 bytes minus overhead on 64-bit platforms. The number of elements that can be stored in a QString is this maximum size divided by the size of QChar.

When memory allocation fails, QString throws a std::bad_alloc exception if the application was compiled with exception support. Out-of-memory conditions in Qt containers are the only cases where Qt will throw exceptions. If exceptions are disabled, then running out of memory is undefined behavior.

Note

Target operating systems may impose limits on how much memory an application can allocate, in total, or on the size of individual allocations. This may further restrict the size of string a QString can hold. Mitigating or controlling the behavior these limits cause is beyond the scope of the Qt API.

See also

fromRawData(), QChar, QStringView, QLatin1StringView, QByteArray

Qt-style synonym for QString::const_iterator.

Definition at line 1050 of file qstring.h.

DataPointer

typedef QStringPrivate QString::DataPointer

Definition at line 206 of file qstring.h.

difference_type

typedef qptrdiff QString::difference_type

Definition at line 1070 of file qstring.h.

Iterator

typedef iterator QString::Iterator

Qt-style synonym for QString::iterator.

Definition at line 1049 of file qstring.h.

iterator

typedef QChar* QString::iterator

See also

QString::const_iterator

Definition at line 1047 of file qstring.h.

pointer

typedef QChar* QString::pointer

The QString::pointer typedef provides an STL-style pointer to a QString element (QChar).

Definition at line 1073 of file qstring.h.

reference

typedef QChar& QString::reference

Definition at line 1072 of file qstring.h.

reverse_iterator

typedef std::reverse_iterator<iterator> QString::reverse_iterator

Since

5.6

See also

QString::const_reverse_iterator, QString::iterator

Definition at line 1051 of file qstring.h.

size_type

typedef qsizetype QString::size_type

Definition at line 1069 of file qstring.h.

value_type

typedef QChar QString::value_type

Definition at line 1075 of file qstring.h.

Member Enumeration Documentation

NormalizationForm

enum QString::NormalizationForm

This enum describes the various normalized forms of Unicode text.

\value NormalizationForm_D Canonical Decomposition \value NormalizationForm_C Canonical Decomposition followed by Canonical Composition \value NormalizationForm_KD Compatibility Decomposition \value NormalizationForm_KC Compatibility Decomposition followed by Canonical Composition

See also

normalized(), {https://www.unicode.org/reports/tr15/}{Unicode Standard Annex #15}

Enumerator
NormalizationForm_D
NormalizationForm_C
NormalizationForm_KD
NormalizationForm_KC

Definition at line 698 of file qstring.h.

SectionFlag

enum QString::SectionFlag

This enum specifies flags that can be used to affect various aspects of the section() function's behavior with respect to separators and empty fields.

\value SectionDefault Empty fields are counted, leading and trailing separators are not included, and the separator is compared case sensitively.

\value SectionSkipEmpty Treat empty fields as if they don't exist, i.e. they are not considered as far as start and end are concerned.

\value SectionIncludeLeadingSep Include the leading separator (if any) in the result string.

\value SectionIncludeTrailingSep Include the trailing separator (if any) in the result string.

\value SectionCaseInsensitiveSeps Compare the separator case-insensitively.

See also

section()

Enumerator
SectionDefault
SectionSkipEmpty
SectionIncludeLeadingSep
SectionIncludeTrailingSep
SectionCaseInsensitiveSeps

Definition at line 416 of file qstring.h.

Constructor & Destructor Documentation

QString() [1/12]

QString::QString ( )

constexprnoexcept

Constructs a null string.

Null strings are also considered empty.

See also

isEmpty(), isNull(), {Distinction Between Null and Empty Strings}

Definition at line 1444 of file qstring.h.

QString() [2/12]

QString::QString ( const QChar * unicode, qsizetype size = -1 )

explicit

Constructs a string initialized with the first size characters of the QChar array unicode.

If unicode is 0, a null string is constructed.

If size is negative, unicode is assumed to point to a '\0'-terminated array and its length is determined dynamically. The terminating null character is not considered part of the string.

QString makes a deep copy of the string data. The unicode data is copied as is and the Byte Order Mark is preserved if present.

See also

fromRawData()

Definition at line 2487 of file qstring.cpp.

QString() [3/12]

QString::QString

(

QChar

c

)

Constructs a string of size 1 containing the character ch.

Definition at line 2553 of file qstring.cpp.

QString() [4/12]

QString::QString	(	qsizetype	size,
		QChar	ch )

Constructs a string of the given size with every character set to ch.

See also

fill()

Definition at line 2511 of file qstring.cpp.

QString() [5/12]

QString::QString ( QLatin1StringView str )

inline

Constructs a copy of the Latin-1 string viewed by str.

See also

fromLatin1()

Definition at line 1344 of file qstring.h.

QString() [6/12]

QString::QString ( QStringView sv )

inlineexplicit

Definition at line 213 of file qstring.h.

QString() [7/12]

QString::QString ( const QString & other )

inlinenoexcept

Constructs a copy of other.

This operation takes \l{constant time}, because QString is \l{implicitly shared}. This makes returning a QString from a function very fast. If a shared instance is modified, it will be copied (copy-on-write), and that takes \l{linear time}.

See also

operator=()

Definition at line 1374 of file qstring.h.

~QString()

QString::~QString ( )

inline

Destroys the string.

Definition at line 1445 of file qstring.h.

QString() [8/12]

QString::QString ( QString && other )

inlinedefaultnoexcept

Move-constructs a QString instance, making it point at the same object that other was pointing to.

Since

5.2

QString() [9/12]

QT_ASCII_CAST_WARN QString::QString ( const char * str )

inline

Constructs a string initialized with the 8-bit string str.

The given const char pointer is converted to Unicode using the fromUtf8() function.

You can disable this constructor by defining \l QT_NO_CAST_FROM_ASCII when you compile your applications. This can be useful if you want to ensure that all user-visible strings go through QObject::tr(), for example.

Note

Defining \l QT_RESTRICTED_CAST_FROM_ASCII also disables this constructor, but enables a {QString(const char (&ch)[N])} constructor instead. Using non-literal input, or input with embedded NUL characters, or non-7-bit characters is undefined in this case.

See also

fromLatin1(), fromLocal8Bit(), fromUtf8()

Definition at line 957 of file qstring.h.

QString() [10/12]

QT_ASCII_CAST_WARN QString::QString ( const QByteArray & ba )

inline

Constructs a string initialized with the byte array ba.

The given byte array is converted to Unicode using fromUtf8().

You can disable this constructor by defining \l QT_NO_CAST_FROM_ASCII when you compile your applications. This can be useful if you want to ensure that all user-visible strings go through QObject::tr(), for example.

Note

Any null ('\0') bytes in the byte array will be included in this string, converted to Unicode null characters (U+0000). This behavior is different from Qt 5.x.

See also

fromLatin1(), fromLocal8Bit(), fromUtf8()

Definition at line 960 of file qstring.h.

QString() [11/12]

QString::QString	(	qsizetype	size,
		Qt::Initialization	)

Constructs a string of the given size without initializing the characters. This is only used in QStringBuilder::toString().

Definition at line 2532 of file qstring.cpp.

QString() [12/12]

QString::QString ( DataPointer && dd )

inlineexplicit

Definition at line 1119 of file qstring.h.

Member Function Documentation

append() [1/8]

QT_ASCII_CAST_WARN QString & QString::append ( const char * s )

inline

Definition at line 984 of file qstring.h.

append() [2/8]

QT_ASCII_CAST_WARN QString & QString::append ( const QByteArray & s )

inline

Definition at line 986 of file qstring.h.

append() [3/8]

QString & QString::append	(	const QChar *	uc,
		qsizetype	len )

Definition at line 3178 of file qstring.cpp.

append() [4/8]

QString & QString::append

(

const QString &

str

)

Appends the string str onto the end of this string.

Example:

    QString x = "free";
    QString y = "dom";
 
    x.append(y);
    // x == "freedom"

This is the same as using the insert() function:

    x.insert(x.size(), y);

The append() function is typically very fast (\l{constant time}), because QString preallocates extra space at the end of the string data so it can grow without reallocating the entire string each time.

See also

operator+=(), prepend(), insert()

Definition at line 3149 of file qstring.cpp.

append() [5/8]

QString & QString::append

(

QChar

c

)

Definition at line 3244 of file qstring.cpp.

append() [6/8]

QString & QString::append

(

QLatin1StringView

s

)

Definition at line 3195 of file qstring.cpp.

append() [7/8]

QString & QString::append ( QStringView v )

inline

Definition at line 553 of file qstring.h.

append() [8/8]

QString & QString::append

(

QUtf8StringView

s

)

Definition at line 3207 of file qstring.cpp.

arg() [1/4]

template<typename... Args>

std::enable_if< sizeof...(Args)>=2 &&std::conjunction_v< is_string_like< Args >... >, QString >::type QString::arg ( Args &&... args ) const

inlinenodiscard

Definition at line 363 of file qstring.h.

arg() [2/4]

template<typename T, if_string_like< T > = true>

QString QString::arg ( const T & a, int fieldWidth = 0, QChar fillChar = u' ' ) const

inlinenodiscard

Returns a copy of this string with the lowest-numbered place-marker replaced by string a, i.e., %1, %2, ..., %99.

fieldWidth specifies the minimum amount of space that a shall occupy. If a requires less space than fieldWidth, it is padded to fieldWidth with character fillChar. A positive fieldWidth produces right-aligned text. A negative fieldWidth produces left-aligned text.

This example shows how we might create a status string for reporting progress while processing a list of files:

    int i;                // current file's number
    int total;            // number of files to process
    QStringView fileName; // current file's name
 
    QString status = QString("Processing file %1 of %2: %3")
                    .arg(i).arg(total).arg(fileName);

First, arg(i) replaces %1. Then arg(total) replaces %2. Finally, arg(fileName) replaces %3.

One advantage of using arg() over asprintf() is that the order of the numbered place markers can change, if the application's strings are translated into other languages, but each arg() will still replace the lowest-numbered unreplaced place-marker, no matter where it appears. Also, if place-marker i appears more than once in the string, arg() replaces all of them.

If there is no unreplaced place-marker remaining, a warning message is printed and the result is undefined. Place-marker numbers must be in the range 1 to 99.

Note

In Qt versions prior to 6.9, this function was overloaded on {char}, QChar, QString, QStringView, and QLatin1StringView and in some cases, {wchar_t} and {char16_t} arguments would resolve to the integer overloads. In Qt versions prior to 5.10, this function lacked the QStringView and QLatin1StringView overloads.

Definition at line 343 of file qstring.h.

arg() [3/4]

template<typename T, if_floating_point< T > = true>

QString QString::arg ( T a, int fieldWidth = 0, char format = 'g', int precision = -1, QChar fillChar = u' ' ) const

inlinenodiscard

Definition at line 338 of file qstring.h.

arg() [4/4]

template<typename T, if_integral_non_char< T > = true>

QString QString::arg ( T a, int fieldWidth = 0, int base = 10, QChar fillChar = u' ' ) const

inlinenodiscard

Definition at line 323 of file qstring.h.

asprintf()

QString QString::asprintf ( const char * cformat, ... )

static

Since

5.5

Safely builds a formatted string from the format string cformat and an arbitrary list of arguments.

The format string supports the conversion specifiers, length modifiers, and flags provided by printf() in the standard C++ library. The cformat string and {s} arguments must be UTF-8 encoded.

Note

The {lc} escape sequence expects a unicode character of type char16_t, or ushort (as returned by QChar::unicode()). The {ls} escape sequence expects a pointer to a zero-terminated array of unicode characters of type char16_t, or ushort (as returned by QString::utf16()). This is at odds with the printf() in the standard C++ library, which defines {lc} to print a wchar_t and {ls} to print a {wchar_t*}, and might also produce compiler warnings on platforms where the size of {wchar_t} is not 16 bits.

Warning

We do not recommend using QString::asprintf() in new Qt code. Instead, consider using QTextStream or arg(), both of which support Unicode strings seamlessly and are type-safe. Here is an example that uses QTextStream:

    QString result;
    QTextStream(&result) << "pi = " << 3.14;
    // result == "pi = 3.14"

For \l {QObject::tr()}{translations}, especially if the strings contains more than one escape sequence, you should consider using the arg() function instead. This allows the order of the replacements to be controlled by the translator.

See also

arg()

Definition at line 7350 of file qstring.cpp.

assign() [1/3]

template<typename InputIterator, if_compatible_iterator< InputIterator > = true>

QString & QString::assign ( InputIterator first, InputIterator last )

inline

Definition at line 571 of file qstring.h.

assign() [2/3]

QString & QString::assign

(

QAnyStringView

v

)

Since

6.6

Replaces the contents of this string with a copy of v and returns a reference to this string.

The size of this string will be equal to the size of v, converted to UTF-16 as if by {v.toString()}. Unlike QAnyStringView::toString(), however, this function only allocates memory if the estimated size exceeds the capacity of this string or this string is shared.

See also

QAnyStringView::toString()

Definition at line 3398 of file qstring.cpp.

assign() [3/3]

QString & QString::assign ( qsizetype n, QChar c )

inline

Since

6.6

Replaces the contents of this string with n copies of c and returns a reference to this string.

The size of this string will be equal to n, which has to be non-negative.

This function will only allocate memory if n exceeds the capacity of this string or this string is shared.

See also

fill()

Definition at line 565 of file qstring.h.

at()

const QChar QString::at ( qsizetype position ) const

inline

Returns the character at the given index position in the string.

The position must be a valid index position in the string (i.e., 0 <= position < size()).

See also

operator[]()

Definition at line 1346 of file qstring.h.

back() [1/2]

QChar & QString::back ( )

inlinenodiscard

Since

5.10

Returns a reference to the last character in the string. Same as {operator[](size() - 1)}.

This function is provided for STL compatibility.

Warning

Calling this function on an empty string constitutes undefined behavior.

See also

front(), at(), operator[]()

Definition at line 1468 of file qstring.h.

back() [2/2]

QChar QString::back ( ) const

inlinenodiscard

Since

5.10

Returns the last character in the string. Same as {at(size() - 1)}.

This function is provided for STL compatibility.

Warning

Calling this function on an empty string constitutes undefined behavior.

See also

front(), at(), operator[]()

Definition at line 288 of file qstring.h.

begin() [1/2]

QString::iterator QString::begin ( )

inline

Returns an \l{STL-style iterators}{STL-style iterator} pointing to the first character in the string.

! [iterator-invalidation-func-desc]

Warning

The returned iterator is invalidated on detachment or when the QString is modified. ! [iterator-invalidation-func-desc]

\sa constBegin(), end()

Definition at line 1469 of file qstring.h.

begin() [2/2]

QString::const_iterator QString::begin ( ) const

inline

Definition at line 1471 of file qstring.h.

capacity()

qsizetype QString::capacity ( ) const

inline

Returns the maximum number of characters that can be stored in the string without forcing a reallocation.

The sole purpose of this function is to provide a means of fine tuning QString's memory usage. In general, you will rarely ever need to call this function. If you want to know how many characters are in the string, call size().

Note

a statically allocated string will report a capacity of 0, even if it's not empty.

The free space position in the allocated memory block is undefined. In other words, one should not assume that the free memory is always located after the initialized elements.

See also

reserve(), squeeze()

Definition at line 1376 of file qstring.h.

cbegin()

QString::const_iterator QString::cbegin ( ) const

inline

Since

5.0

Returns a const \l{STL-style iterators}{STL-style iterator} pointing to the first character in the string.

iterator-invalidation-func-desc

See also

begin(), cend()

Definition at line 1473 of file qstring.h.

cend()

QString::const_iterator QString::cend ( ) const

inline

Since

5.0

Returns a const \l{STL-style iterators}{STL-style iterator} pointing just after the last character in the string.

iterator-invalidation-func-desc

See also

cbegin(), end()

Definition at line 1481 of file qstring.h.

chop()

void QString::chop

(

qsizetype

n

)

Removes n characters from the end of the string.

If n is greater than or equal to size(), the result is an empty string; if n is negative, it is equivalent to passing zero.

Example:

    QString str("LOGOUT\r\n");
    str.chop(2);
    // str == "LOGOUT"

If you want to remove characters from the beginning of the string, use remove() instead.

See also

truncate(), resize(), remove(), QStringView::chop()

Definition at line 6389 of file qstring.cpp.

chopped() [1/2]

QString QString::chopped ( qsizetype n ) &&

inlinenodiscard

Definition at line 492 of file qstring.h.

chopped() [2/2]

QString QString::chopped ( qsizetype n ) const &

inlinenodiscard

Definition at line 477 of file qstring.h.

clear()

void QString::clear ( )

inline

Clears the contents of the string and makes it null.

See also

resize(), isNull()

Definition at line 1372 of file qstring.h.

compare() [1/9]

int QString::compare ( const QString & s, Qt::CaseSensitivity cs = Qt::CaseSensitive ) const

noexcept

Definition at line 6723 of file qstring.cpp.

compare() [2/9]

static int QString::compare ( const QString & s1, const QString & s2, Qt::CaseSensitivity cs = Qt::CaseSensitive )

inlinestaticnoexcept

Definition at line 824 of file qstring.h.

compare() [3/9]

static int QString::compare ( const QString & s1, QLatin1StringView s2, Qt::CaseSensitivity cs = Qt::CaseSensitive )

inlinestaticnoexcept

Definition at line 828 of file qstring.h.

compare() [4/9]

static int QString::compare ( const QString & s1, QStringView s2, Qt::CaseSensitivity cs = Qt::CaseSensitive )

inlinestaticnoexcept

Definition at line 834 of file qstring.h.

compare() [5/9]

int QString::compare ( QChar ch, Qt::CaseSensitivity cs = Qt::CaseSensitive ) const

inlinenoexcept

Definition at line 821 of file qstring.h.

compare() [6/9]

int QString::compare ( QLatin1StringView other, Qt::CaseSensitivity cs = Qt::CaseSensitive ) const

noexcept

Definition at line 6748 of file qstring.cpp.

compare() [7/9]

static int QString::compare ( QLatin1StringView s1, const QString & s2, Qt::CaseSensitivity cs = Qt::CaseSensitive )

inlinestaticnoexcept

Definition at line 831 of file qstring.h.

compare() [8/9]

int QString::compare ( QStringView s, Qt::CaseSensitivity cs = Qt::CaseSensitive ) const

inlinenoexcept

Definition at line 1621 of file qstring.h.

compare() [9/9]

static int QString::compare ( QStringView s1, const QString & s2, Qt::CaseSensitivity cs = Qt::CaseSensitive )

inlinestaticnoexcept

Definition at line 836 of file qstring.h.

constBegin()

QString::const_iterator QString::constBegin ( ) const

inline

Returns a const \l{STL-style iterators}{STL-style iterator} pointing to the first character in the string.

iterator-invalidation-func-desc

See also

begin(), constEnd()

Definition at line 1475 of file qstring.h.

constData()

const QChar * QString::constData ( ) const

inline

Returns a pointer to the data stored in the QString.

The pointer can be used to access the characters that compose the string.

Note that the pointer remains valid only as long as the string is not modified.

Note

The returned string may not be '\0'-terminated. Use size() to determine the length of the array.

See also

data(), operator[](), fromRawData()

Definition at line 1366 of file qstring.h.

constEnd()

QString::const_iterator QString::constEnd ( ) const

inline

Returns a const \l{STL-style iterators}{STL-style iterator} pointing just after the last character in the string.

iterator-invalidation-func-desc

See also

constBegin(), end()

Definition at line 1483 of file qstring.h.

contains() [1/4]

bool QString::contains ( const QString & str, Qt::CaseSensitivity cs = Qt::CaseSensitive ) const

inlinenodiscard

Returns true if this string contains an occurrence of the string str; otherwise returns false.

{search-comparison-case-sensitivity} {search}

Example:

    QString str = "Peter Pan";
    str.contains("peter", Qt::CaseInsensitive);    // returns true

See also

indexOf(), count()

Definition at line 1485 of file qstring.h.

contains() [2/4]

bool QString::contains ( QChar c, Qt::CaseSensitivity cs = Qt::CaseSensitive ) const

inlinenodiscard

Definition at line 1489 of file qstring.h.

contains() [3/4]

bool QString::contains ( QLatin1StringView s, Qt::CaseSensitivity cs = Qt::CaseSensitive ) const

inlinenodiscard

Definition at line 1487 of file qstring.h.

contains() [4/4]

bool QString::contains ( QStringView s, Qt::CaseSensitivity cs = Qt::CaseSensitive ) const

inlinenodiscardnoexcept

Definition at line 1491 of file qstring.h.

count() [1/3]

qsizetype QString::count ( const QString & str, Qt::CaseSensitivity cs = Qt::CaseSensitive ) const

nodiscard

Returns the number of (potentially overlapping) occurrences of the string str in this string.

{search-comparison-case-sensitivity} {search}

See also

contains(), indexOf()

Definition at line 4826 of file qstring.cpp.

count() [2/3]

qsizetype QString::count ( QChar c, Qt::CaseSensitivity cs = Qt::CaseSensitive ) const

nodiscard

Definition at line 4841 of file qstring.cpp.

count() [3/3]

qsizetype QString::count ( QStringView s, Qt::CaseSensitivity cs = Qt::CaseSensitive ) const

nodiscard

Definition at line 4856 of file qstring.cpp.

crbegin()

const_reverse_iterator QString::crbegin ( ) const

inline

Since

5.6

Returns a const \l{STL-style iterators}{STL-style} reverse iterator pointing to the first character in the string, in reverse order.

iterator-invalidation-func-desc

See also

begin(), rbegin(), rend()

Definition at line 1065 of file qstring.h.

crend()

const_reverse_iterator QString::crend ( ) const

inline

Since

5.6

Returns a const \l{STL-style iterators}{STL-style} reverse iterator pointing just after the last character in the string, in reverse order.

iterator-invalidation-func-desc

See also

end(), rend(), rbegin()

Definition at line 1066 of file qstring.h.

data() [1/2]

QChar * QString::data ( )

inline

Returns a pointer to the data stored in the QString.

The pointer can be used to access and modify the characters that compose the string.

Unlike constData() and unicode(), the returned data is always '\0'-terminated.

Example:

    QString str = "Hello world";
    QChar *data = str.data();
    while (!data->isNull()) {
        qDebug() << data->unicode();
        ++data;
    }

Note that the pointer remains valid only as long as the string is not modified by other means. For read-only access, constData() is faster because it never causes a \l{deep copy} to occur.

See also

constData(), operator[]()

Definition at line 1360 of file qstring.h.

data() [2/2]

const QChar * QString::data ( ) const

inline

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Note

The returned string may not be '\0'-terminated. Use size() to determine the length of the array.

See also

fromRawData()

Definition at line 1352 of file qstring.h.

data_ptr() [1/2]

DataPointer & QString::data_ptr ( )

inline

Definition at line 1213 of file qstring.h.

data_ptr() [2/2]

const DataPointer & QString::data_ptr ( ) const

inline

Definition at line 1214 of file qstring.h.

detach()

void QString::detach ( )

inline

Definition at line 1368 of file qstring.h.

end() [1/2]

QString::iterator QString::end ( )

inline

Returns an \l{STL-style iterators}{STL-style iterator} pointing just after the last character in the string.

iterator-invalidation-func-desc

See also

begin(), constEnd()

Definition at line 1477 of file qstring.h.

end() [2/2]

QString::const_iterator QString::end ( ) const

inline

Definition at line 1479 of file qstring.h.

endsWith() [1/4]

bool QString::endsWith	(	const QString &	s,
		Qt::CaseSensitivity	cs = Qt::CaseSensitive ) const

Returns true if the string ends with s; otherwise returns false.

{search-comparison-case-sensitivity} {search}

    QString str = "Bananas";
    str.endsWith("anas");         // returns true
    str.endsWith("pple");         // returns false

See also

startsWith()

Definition at line 5519 of file qstring.cpp.

endsWith() [2/4]

bool QString::endsWith	(	QChar	c,
		Qt::CaseSensitivity	cs = Qt::CaseSensitive ) const

Definition at line 5550 of file qstring.cpp.

endsWith() [3/4]

bool QString::endsWith	(	QLatin1StringView	s,
		Qt::CaseSensitivity	cs = Qt::CaseSensitive ) const

Definition at line 5539 of file qstring.cpp.

endsWith() [4/4]

bool QString::endsWith ( QStringView s, Qt::CaseSensitivity cs = Qt::CaseSensitive ) const

inlinenodiscardnoexcept

Definition at line 502 of file qstring.h.

erase() [1/2]

QString::iterator QString::erase	(	QString::const_iterator	first,
		QString::const_iterator	last )

Since

6.1

Removes from the string the characters in the half-open range [ first , last ). Returns an iterator to the character immediately after the last erased character (i.e. the character referred to by last before the erase).

Definition at line 9331 of file qstring.cpp.

erase() [2/2]

iterator QString::erase ( QString::const_iterator it )

inline

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Since

6.5

Removes the character denoted by it from the string. Returns an iterator to the character immediately after the erased character.

QString c = "abcdefg";
auto it = c.erase(c.cbegin()); // c is now "bcdefg"; "it" points to "b"

Definition at line 1082 of file qstring.h.

fill()

QString & QString::fill	(	QChar	ch,
		qsizetype	size = -1 )

Sets every character in the string to character ch.

If size is different from -1 (default), the string is resized to size beforehand.

Example:

    QString str = "Berlin";
    str.fill('z');
    // str == "zzzzzz"
 
    str.fill('A', 2);
    // str == "AA"

See also

resize()

Definition at line 6407 of file qstring.cpp.

first() [1/2]

QString QString::first ( qsizetype n ) &&

inlinenodiscard

Definition at line 480 of file qstring.h.

first() [2/2]

QString QString::first ( qsizetype n ) const &

inlinenodiscard

Definition at line 469 of file qstring.h.

fromLatin1() [1/3]

static QString QString::fromLatin1 ( const char * str, qsizetype size )

inlinestatic

Returns a QString initialized with the first size characters of the Latin-1 string str.

If size is {-1}, {strlen(str)} is used instead.

See also

toLatin1(), fromUtf8(), fromLocal8Bit()

Definition at line 757 of file qstring.h.

fromLatin1() [2/3]

static Q_WEAK_OVERLOAD QString QString::fromLatin1 ( const QByteArray & str )

inlinestatic

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Since

5.0

Returns a QString initialized with the Latin-1 string str.

Note

: any null ('\0') bytes in the byte array will be included in this string, converted to Unicode null characters (U+0000). This behavior is different from Qt 5.x.

Definition at line 756 of file qstring.h.

fromLatin1() [3/3]

QString QString::fromLatin1 ( QByteArrayView str )

static

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Since

6.0

Returns a QString initialized with the Latin-1 string str.

Note

: any null ('\0') bytes in the byte array will be included in this string, converted to Unicode null characters (U+0000).

Definition at line 5904 of file qstring.cpp.

fromLocal8Bit() [1/3]

static QString QString::fromLocal8Bit ( const char * str, qsizetype size )

inlinestatic

Returns a QString initialized with the first size characters of the 8-bit string str.

If size is {-1}, {strlen(str)} is used instead.

{qstring-local-8-bit-equivalent} {fromUtf8}

See also

toLocal8Bit(), fromLatin1(), fromUtf8()

Definition at line 779 of file qstring.h.

fromLocal8Bit() [2/3]

static Q_WEAK_OVERLOAD QString QString::fromLocal8Bit ( const QByteArray & str )

inlinestatic

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Since

5.0

Returns a QString initialized with the 8-bit string str.

{qstring-local-8-bit-equivalent} {fromUtf8}

Note

: any null ('\0') bytes in the byte array will be included in this string, converted to Unicode null characters (U+0000). This behavior is different from Qt 5.x.

Definition at line 778 of file qstring.h.

fromLocal8Bit() [3/3]

QString QString::fromLocal8Bit ( QByteArrayView str )

static

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Since

6.0

Returns a QString initialized with the 8-bit string str.

{qstring-local-8-bit-equivalent} {fromUtf8}

Note

: any null ('\0') bytes in the byte array will be included in this string, converted to Unicode null characters (U+0000).

Definition at line 5982 of file qstring.cpp.

fromRawData() [1/2]

static QString QString::fromRawData ( const char16_t * unicode, qsizetype size )

inlinestatic

Since

6.10

Constructs a QString that uses the first size Unicode characters in the array unicode. The data in unicode is not copied. The caller must be able to guarantee that unicode will not be deleted or modified as long as the QString (or an unmodified copy of it) exists.

Any attempts to modify the QString or copies of it will cause it to create a deep copy of the data, ensuring that the raw data isn't modified.

Here is an example of how we can use a QRegularExpression on raw data in memory without requiring to copy the data into a QString:

    QRegularExpression pattern("\u00A4");
    static const char16_t unicode[] = {
            0x005A, 0x007F, 0x00A4, 0x0060,
            0x1009, 0x0020, 0x0020};
 
    QString str = QString::fromRawData(unicode, std::size(unicode));
    if (str.contains(pattern) {
        // ...

    }

Warning

A string created with fromRawData() is not '\0'-terminated, unless the raw data contains a '\0' character at position size. This means unicode() will not return a '\0'-terminated string (although utf16() does, at the cost of copying the raw data).

See also

fromUtf16(), setRawData(), data(), constData(), nullTerminate(), nullTerminated()

Definition at line 785 of file qstring.h.

fromRawData() [2/2]

static QString QString::fromRawData ( const QChar * unicode, qsizetype size )

static

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

fromStdString()

QString QString::fromStdString ( const std::string & str )

inlinestatic

{from-std-string} {UTF-8} {fromUtf8()}

See also

fromLatin1(), fromLocal8Bit(), fromUtf8(), QByteArray::fromStdString()

Definition at line 1576 of file qstring.h.

fromStdU16String()

QString QString::fromStdU16String ( const std::u16string & str )

inlinestatic

Since

5.5

{from-std-string} {UTF-16} {fromUtf16()}

See also

fromUtf16(), fromStdWString(), fromStdU32String()

Definition at line 1590 of file qstring.h.

fromStdU32String()

QString QString::fromStdU32String ( const std::u32string & str )

inlinestatic

Since

5.5

{from-std-string} {UTF-32} {fromUcs4()}

See also

fromUcs4(), fromStdWString(), fromStdU16String()

Definition at line 1596 of file qstring.h.

fromStdWString()

QString QString::fromStdWString ( const std::wstring & str )

inlinestatic

Returns a copy of the str string.

The given string is assumed to be encoded in utf16 if the size of wchar_t is 2 bytes (e.g. on windows) and ucs4 if the size of wchar_t is 4 bytes (most Unix systems).

See also

fromUtf16(), fromLatin1(), fromLocal8Bit(), fromUtf8(), fromUcs4(), fromStdU16String(), fromStdU32String()

Definition at line 1587 of file qstring.h.

fromUcs4()

QString QString::fromUcs4 ( const char32_t * unicode, qsizetype size = -1 )

static

Since

4.2

Deprecated

[6.0] Use the char32_t overload instead.

Since

5.3

Returns a QString initialized with the first size characters of the Unicode string unicode (encoded as UTF-32).

If size is -1 (default), unicode must be '\0'-terminated.

See also

toUcs4(), fromUtf16(), utf16(), setUtf16(), fromWCharArray(), fromStdU32String()

Since

4.2

Deprecated

[6.0] Use the char32_t overload instead.

Definition at line 6110 of file qstring.cpp.

fromUtf16()

QString QString::fromUtf16 ( const char16_t * unicode, qsizetype size = -1 )

static

Since

5.3 Returns a QString initialized with the first size characters of the Unicode string unicode (ISO-10646-UTF-16 encoded).

If size is -1 (default), unicode must be '\0'-terminated.

This function checks for a Byte Order Mark (BOM). If it is missing, host byte order is assumed.

This function is slow compared to the other Unicode conversions. Use QString(const QChar *, qsizetype) or QString(const QChar *) if possible.

QString makes a deep copy of the Unicode data.

See also

utf16(), setUtf16(), fromStdU16String()

Deprecated

[6.0] Use the char16_t overload instead.

Deprecated

[6.0] Use the char16_t overload instead.

Definition at line 6078 of file qstring.cpp.

fromUtf8() [1/3]

static QString QString::fromUtf8 ( const char * str, qsizetype size )

inlinestatic

Returns a QString initialized with the first size bytes of the UTF-8 string str.

If size is {-1}, {strlen(str)} is used instead.

UTF-8 is a Unicode codec and can represent all characters in a Unicode string like QString. However, invalid sequences are possible with UTF-8 and, if any such are found, they will be replaced with one or more "replacement characters", or suppressed. These include non-Unicode sequences, non-characters, overlong sequences or surrogate codepoints encoded into UTF-8.

This function can be used to process incoming data incrementally as long as all UTF-8 characters are terminated within the incoming data. Any unterminated characters at the end of the string will be replaced or suppressed. In order to do stateful decoding, please use \l QStringDecoder.

See also

toUtf8(), fromLatin1(), fromLocal8Bit()

Definition at line 764 of file qstring.h.

fromUtf8() [2/3]

static Q_WEAK_OVERLOAD QString QString::fromUtf8 ( const QByteArray & str )

inlinestatic

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Since

5.0

Returns a QString initialized with the UTF-8 string str.

Note

: any null ('\0') bytes in the byte array will be included in this string, converted to Unicode null characters (U+0000). This behavior is different from Qt 5.x.

Definition at line 763 of file qstring.h.

fromUtf8() [3/3]

QString QString::fromUtf8 ( QByteArrayView str )

static

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Since

6.0

Returns a QString initialized with the UTF-8 string str.

Note

: any null ('\0') bytes in the byte array will be included in this string, converted to Unicode null characters (U+0000).

Definition at line 6051 of file qstring.cpp.

fromWCharArray()

QT_WARNING_POP QString QString::fromWCharArray ( const wchar_t * string, qsizetype size = -1 )

inlinestaticnodiscard

Since

4.2

Reads the first size code units of the wchar_t array to whose start string points, converting them to Unicode and returning the result as a QString. The encoding used by wchar_t is assumed to be UTF-32 if the type's size is four bytes or UTF-16 if its size is two bytes.

If size is -1 (default), the string must be '\0'-terminated.

See also

fromUtf16(), fromLatin1(), fromLocal8Bit(), fromUtf8(), fromUcs4(), fromStdWString()

Definition at line 1431 of file qstring.h.

front() [1/2]

QChar & QString::front ( )

inlinenodiscard

Since

5.10

Returns a reference to the first character in the string. Same as {operator[](0)}.

This function is provided for STL compatibility.

Warning

Calling this function on an empty string constitutes undefined behavior.

See also

back(), at(), operator[]()

Definition at line 1467 of file qstring.h.

front() [2/2]

QChar QString::front ( ) const

inlinenodiscard

Since

5.10

Returns the first character in the string. Same as {at(0)}.

This function is provided for STL compatibility.

Warning

Calling this function on an empty string constitutes undefined behavior.

See also

back(), at(), operator[]()

Definition at line 286 of file qstring.h.

indexOf() [1/3]

qsizetype QString::indexOf ( const QString & str, qsizetype from = 0, Qt::CaseSensitivity cs = Qt::CaseSensitive ) const

nodiscard

{qstring-first-index-of} {string} {str}

{search-comparison-case-sensitivity} {search}

Example:

    QString x = "sticky question";
    QString y = "sti";
    x.indexOf(y);               // returns 0
    x.indexOf(y, 1);            // returns 10
    x.indexOf(y, 10);           // returns 10
    x.indexOf(y, 11);           // returns -1

negative-index-start-search-from-end

See also

lastIndexOf(), contains(), count()

Definition at line 4490 of file qstring.cpp.

indexOf() [2/3]

qsizetype QString::indexOf ( QLatin1StringView str, qsizetype from = 0, Qt::CaseSensitivity cs = Qt::CaseSensitive ) const

nodiscard

Since

4.5

} {qstring-first-index-of} {Latin-1 string viewed by} {str}

{search-comparison-case-sensitivity} {search}

Example:

    QString x = "sticky question";
    QString y = "sti";
    x.indexOf(y);               // returns 0
    x.indexOf(y, 1);            // returns 10
    x.indexOf(y, 10);           // returns 10
    x.indexOf(y, 11);           // returns -1

negative-index-start-search-from-end

See also

lastIndexOf(), contains(), count()

Definition at line 4525 of file qstring.cpp.

indexOf() [3/3]

qsizetype QString::indexOf ( QStringView s, qsizetype from = 0, Qt::CaseSensitivity cs = Qt::CaseSensitive ) const

inlinenodiscardnoexcept

Definition at line 373 of file qstring.h.

insert() [1/8]

QT_ASCII_CAST_WARN QString & QString::insert ( qsizetype i, const char * s )

inline

Definition at line 988 of file qstring.h.

insert() [2/8]

QT_ASCII_CAST_WARN QString & QString::insert ( qsizetype i, const QByteArray & s )

inline

Definition at line 990 of file qstring.h.

insert() [3/8]

QString & QString::insert	(	qsizetype	i,
		const QChar *	uc,
		qsizetype	len )

Definition at line 3097 of file qstring.cpp.

insert() [4/8]

QString & QString::insert ( qsizetype i, const QString & s )

inline

Definition at line 545 of file qstring.h.

insert() [5/8]

QString & QString::insert	(	qsizetype	i,
		QChar	c )

Definition at line 3124 of file qstring.cpp.

insert() [6/8]

QString & QString::insert	(	qsizetype	i,
		QLatin1StringView	s )

Definition at line 3017 of file qstring.cpp.

insert() [7/8]

QString & QString::insert ( qsizetype i, QStringView v )

inline

Definition at line 546 of file qstring.h.

insert() [8/8]

QString & QString::insert	(	qsizetype	i,
		QUtf8StringView	s )

Definition at line 3040 of file qstring.cpp.

isDetached()

bool QString::isDetached ( ) const

inline

Definition at line 1370 of file qstring.h.

isEmpty()

bool QString::isEmpty ( ) const

inlineconstexprnoexcept

Returns true if the string has no characters; otherwise returns false.

Example:

    QString().isEmpty();            // returns true
    QString("").isEmpty();          // returns true
    QString("x").isEmpty();         // returns false
    QString("abc").isEmpty();       // returns false

See also

size()

Definition at line 248 of file qstring.h.

isLower()

bool QString::isLower

(

)

const

Returns true if the string is lowercase, that is, it's identical to its toLower() folding.

Note that this does not mean that the string does not contain uppercase letters (some uppercase letters do not have a lowercase folding; they are left unchanged by toLower()). For more information, refer to the Unicode standard, section 3.13.

Since

5.12

See also

QChar::toLower(), isUpper()

Definition at line 5611 of file qstring.cpp.

isNull()

bool QString::isNull ( ) const

inlineconstexpr

Returns true if this string is null; otherwise returns false.

Example:

    QString().isNull();             // returns true
    QString("").isNull();           // returns false
    QString("abc").isNull();        // returns false

Qt makes a distinction between null strings and empty strings for historical reasons. For most applications, what matters is whether or not a string contains any data, and this can be determined using the isEmpty() function.

See also

isEmpty()

Definition at line 1112 of file qstring.h.

isRightToLeft()

bool QString::isRightToLeft

(

)

const

Returns true if the string is read right to left.

See also

QStringView::isRightToLeft()

Definition at line 9227 of file qstring.cpp.

isSharedWith()

bool QString::isSharedWith ( const QString & other ) const

inline

Definition at line 279 of file qstring.h.

isUpper()

bool QString::isUpper

(

)

const

Returns true if the string is uppercase, that is, it's identical to its toUpper() folding.

Note that this does not mean that the string does not contain lowercase letters (some lowercase letters do not have a uppercase folding; they are left unchanged by toUpper()). For more information, refer to the Unicode standard, section 3.13.

Since

5.12

See also

QChar::toUpper(), isLower()

Definition at line 5593 of file qstring.cpp.

isValidUtf16()

bool QString::isValidUtf16 ( ) const

inlinenodiscardnoexcept

Since

5.15

Returns true if the string contains valid UTF-16 encoded data, or false otherwise.

Note that this function does not perform any special validation of the data; it merely checks if it can be successfully decoded from UTF-16. The data is assumed to be in host byte order; the presence of a BOM is meaningless.

See also

QStringView::isValidUtf16()

Definition at line 1115 of file qstring.h.

last() [1/2]

QString QString::last ( qsizetype n ) &&

inlinenodiscard

Definition at line 486 of file qstring.h.

last() [2/2]

QString QString::last ( qsizetype n ) const &

inlinenodiscard

Definition at line 471 of file qstring.h.

lastIndexOf() [1/7]

qsizetype QString::lastIndexOf ( const QString & str, qsizetype from, Qt::CaseSensitivity cs = Qt::CaseSensitive ) const

nodiscard

{qstring-last-index-of} {string} {str}

negative-index-start-search-from-end

Returns -1 if str is not found.

{search-comparison-case-sensitivity} {search}

Example:

    QString x = "crazy azimuths";
    QString y = "az";
    x.lastIndexOf(y);           // returns 6
    x.lastIndexOf(y, 6);        // returns 6
    x.lastIndexOf(y, 5);        // returns 2
    x.lastIndexOf(y, 1);        // returns -1

Note

When searching for a 0-length str, the match at the end of the data is excluded from the search by a negative from, even though {-1} is normally thought of as searching from the end of the string: the match at the end is after the last character, so it is excluded. To include such a final empty match, either give a positive value for from or omit the from parameter entirely.

See also

indexOf(), contains(), count()

Definition at line 4559 of file qstring.cpp.

lastIndexOf() [2/7]

qsizetype QString::lastIndexOf ( const QString & s, Qt::CaseSensitivity cs = Qt::CaseSensitive ) const

inlinenodiscard

Definition at line 382 of file qstring.h.

lastIndexOf() [3/7]

qsizetype QString::lastIndexOf ( QChar c, Qt::CaseSensitivity cs = Qt::CaseSensitive ) const

inlinenodiscardnoexcept

Definition at line 375 of file qstring.h.

lastIndexOf() [4/7]

qsizetype QString::lastIndexOf ( QLatin1StringView s, qsizetype from, Qt::CaseSensitivity cs = Qt::CaseSensitive ) const

nodiscard

Definition at line 4607 of file qstring.cpp.

lastIndexOf() [5/7]

qsizetype QString::lastIndexOf ( QLatin1StringView s, Qt::CaseSensitivity cs = Qt::CaseSensitive ) const

inlinenodiscard

Definition at line 379 of file qstring.h.

lastIndexOf() [6/7]

qsizetype QString::lastIndexOf ( QStringView s, qsizetype from, Qt::CaseSensitivity cs = Qt::CaseSensitive ) const

inlinenodiscardnoexcept

Definition at line 388 of file qstring.h.

lastIndexOf() [7/7]

qsizetype QString::lastIndexOf ( QStringView s, Qt::CaseSensitivity cs = Qt::CaseSensitive ) const

inlinenodiscardnoexcept

Definition at line 386 of file qstring.h.

left() [1/2]

QString QString::left ( qsizetype n ) &&

inlinenodiscard

Definition at line 448 of file qstring.h.

left() [2/2]

QString QString::left ( qsizetype n ) const &

inlinenodiscard

Definition at line 442 of file qstring.h.

leftJustified()

QString QString::leftJustified ( qsizetype width, QChar fill = u' ', bool truncate = false ) const

nodiscard

Returns a string of size width that contains this string padded by the fill character.

If truncate is false and the size() of the string is more than width, then the returned string is a copy of the string.

    QString s = "apple";
    QString t = s.leftJustified(8, '.');    // t == "apple..."

If truncate is true and the size() of the string is more than width, then any characters in a copy of the string after position width are removed, and the copy is returned.

    QString str = "Pineapple";
    str = str.leftJustified(5, '.', true);    // str == "Pinea"

See also

rightJustified()

Definition at line 7106 of file qstring.cpp.

length()

qsizetype QString::length ( ) const

inlineconstexprnoexcept

Returns the number of characters in this string.

Equivalent to size().

See also

resize()

Definition at line 247 of file qstring.h.

localeAwareCompare() [1/4]

int QString::localeAwareCompare

(

const QString &

s

)

const

Definition at line 6966 of file qstring.cpp.

localeAwareCompare() [2/4]

static int QString::localeAwareCompare ( const QString & s1, const QString & s2 )

inlinestatic

Compares s1 with s2 and returns an integer less than, equal to, or greater than zero if s1 is less than, equal to, or greater than s2.

The comparison is performed in a locale- and also platform-dependent manner. Use this function to present sorted lists of strings to the user.

See also

compare(), QLocale, {Comparing Strings}

Definition at line 841 of file qstring.h.

localeAwareCompare() [3/4]

int QString::localeAwareCompare ( QStringView s ) const

inline

Definition at line 1624 of file qstring.h.

localeAwareCompare() [4/4]

int QString::localeAwareCompare ( QStringView s1, QStringView s2 )

inlinestatic

Definition at line 1626 of file qstring.h.

max_size()

qsizetype QString::max_size ( ) const

inlineconstexprnoexcept

Definition at line 1083 of file qstring.h.

maxSize()

static constexpr qsizetype QString::maxSize ( )

inlinestaticconstexprnoexcept

Since

6.8

It returns the maximum number of elements that the string can theoretically hold. In practice, the number can be much smaller, limited by the amount of memory available to the system.

Definition at line 230 of file qstring.h.

mid() [1/2]

QString QString::mid ( qsizetype position, qsizetype n = -1 ) &&

nodiscard

Definition at line 5328 of file qstring.cpp.

mid() [2/2]

QString QString::mid ( qsizetype position, qsizetype n = -1 ) const &

nodiscard

Definition at line 5310 of file qstring.cpp.

normalized()

QString QString::normalized ( QString::NormalizationForm mode, QChar::UnicodeVersion version = QChar::Unicode_Unassigned ) const

nodiscard

Returns the string in the given Unicode normalization mode, according to the given version of the Unicode standard.

Definition at line 8562 of file qstring.cpp.

nullTerminate()

QString & QString::nullTerminate ( )

inline

Since

6.10

If this string data isn't null-terminated, this method will make a deep copy of the data and make it null-terminated.

A QString is null-terminated by default, however in some cases (e.g. when using fromRawData()), the string data doesn't necessarily end with a {\0} character, which could be a problem when calling methods that expect a null-terminated string.

See also

nullTerminated(), fromRawData(), setRawData()

Definition at line 725 of file qstring.h.

nullTerminated() [1/2]

QString QString::nullTerminated ( ) &&

inlinenodiscard

Definition at line 717 of file qstring.h.

nullTerminated() [2/2]

QString QString::nullTerminated ( ) const &

inlinenodiscard

Definition at line 709 of file qstring.h.

number() [1/7]

QString QString::number ( double n, char format = 'g', int precision = 6 )

static

Returns a string representing the floating-point number n.

Returns a string that represents n, formatted according to the specified format and precision.

For formats with an exponent, the exponent will show its sign and have at least two digits, left-padding the exponent with zero if needed.

See also

setNum(), QLocale::toString(), QLocale::FloatingPointPrecisionOption, {Number Formats}

Definition at line 8229 of file qstring.cpp.

number() [2/7]

QString QString::number ( int n, int base = 10 )

static

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 8171 of file qstring.cpp.

number() [3/7]

QString QString::number ( long n, int base = 10 )

static

Returns a string equivalent of the number n according to the specified base.

The base is 10 by default and must be between 2 and 36. For bases other than 10, n is treated as an unsigned integer.

The formatting always uses QLocale::C, i.e., English/UnitedStates. To get a localized string representation of a number, use QLocale::toString() with the appropriate locale.

    long a = 63;
    QString s = QString::number(a, 16);             // s == "3f"
    QString t = QString::number(a, 16).toUpper();     // t == "3F"

See also

setNum()

Definition at line 8153 of file qstring.cpp.

number() [4/7]

QString QString::number ( qlonglong n, int base = 10 )

static

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 8187 of file qstring.cpp.

number() [5/7]

QString QString::number ( qulonglong n, int base = 10 )

static

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 8206 of file qstring.cpp.

number() [6/7]

QString QString::number ( uint n, int base = 10 )

static

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 8179 of file qstring.cpp.

number() [7/7]

QString QString::number ( ulong n, int base = 10 )

static

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 8163 of file qstring.cpp.

operator std::u16string_view()

QString::operator std::u16string_view ( ) const

inlinenoexcept

Since

6.7

Converts this QString object to a {std::u16string_view} object.

Definition at line 1608 of file qstring.h.

operator+=() [1/7]

QT_ASCII_CAST_WARN QString & QString::operator+= ( const char * s )

inline

Definition at line 992 of file qstring.h.

operator+=() [2/7]

QT_ASCII_CAST_WARN QString & QString::operator+= ( const QByteArray & s )

inline

Definition at line 994 of file qstring.h.

operator+=() [3/7]

QString & QString::operator+= ( const QString & other )

inline

Appends the string other onto the end of this string and returns a reference to this string.

Example:

    QString x = "free";
    QString y = "dom";
    x += y;
    // x == "freedom"

This operation is typically very fast (\l{constant time}), because QString preallocates extra space at the end of the string data so it can grow without reallocating the entire string each time.

See also

append(), prepend()

Definition at line 615 of file qstring.h.

operator+=() [4/7]

QString & QString::operator+= ( QChar c )

inline

Definition at line 613 of file qstring.h.

operator+=() [5/7]

QString & QString::operator+= ( QLatin1StringView s )

inline

Definition at line 617 of file qstring.h.

operator+=() [6/7]

QString & QString::operator+= ( QStringView v )

inline

Definition at line 616 of file qstring.h.

operator+=() [7/7]

QString & QString::operator+= ( QUtf8StringView s )

inline

Definition at line 618 of file qstring.h.

operator=() [1/5]

QT_ASCII_CAST_WARN QString & QString::operator= ( const char * ch )

inline

Definition at line 963 of file qstring.h.

operator=() [2/5]

QT_ASCII_CAST_WARN QString & QString::operator= ( const QByteArray & a )

inline

Definition at line 971 of file qstring.h.

operator=() [3/5]

QString & QString::operator= ( const QString & other )

noexcept

Assigns other to this string and returns a reference to this string.

Definition at line 2829 of file qstring.cpp.

operator=() [4/5]

QString & QString::operator=

(

QChar

c

)

Definition at line 2893 of file qstring.cpp.

operator=() [5/5]

QString & QString::operator=

(

QLatin1StringView

latin1

)

Definition at line 2849 of file qstring.cpp.

operator[]() [1/2]

QChar & QString::operator[] ( qsizetype position )

inlinenodiscard

Returns the character at the specified position in the string as a modifiable reference.

Example:

    QString str;
 
    if (str[0] == QChar('?'))
        str[0] = QChar('_');

See also

at()

Definition at line 1465 of file qstring.h.

operator[]() [2/2]

const QChar QString::operator[] ( qsizetype i ) const

inline

Definition at line 1348 of file qstring.h.

prepend() [1/8]

QT_ASCII_CAST_WARN QString & QString::prepend ( const char * s )

inline

Definition at line 980 of file qstring.h.

prepend() [2/8]

QT_ASCII_CAST_WARN QString & QString::prepend ( const QByteArray & s )

inline

Definition at line 982 of file qstring.h.

prepend() [3/8]

QString & QString::prepend ( const QChar * uc, qsizetype len )

inline

Definition at line 558 of file qstring.h.

prepend() [4/8]

QString & QString::prepend ( const QString & str )

inline

Prepends the string str to the beginning of this string and returns a reference to this string.

This operation is typically very fast (\l{constant time}), because QString preallocates extra space at the beginning of the string data, so it can grow without reallocating the entire string each time.

Example:

    QString x = "ship";
    QString y = "air";
    x.prepend(y);
    // x == "airship"

See also

append(), insert()

Definition at line 559 of file qstring.h.

prepend() [5/8]

QString & QString::prepend ( QChar c )

inline

Definition at line 557 of file qstring.h.

prepend() [6/8]

QString & QString::prepend ( QLatin1StringView s )

inline

Definition at line 561 of file qstring.h.

prepend() [7/8]

QString & QString::prepend ( QStringView v )

inline

Definition at line 560 of file qstring.h.

prepend() [8/8]

QString & QString::prepend ( QUtf8StringView s )

inline

Definition at line 562 of file qstring.h.

push_back() [1/2]

void QString::push_back ( const QString & other )

inline

This function is provided for STL compatibility, appending the given other string onto the end of this string.

It is equivalent to append(other).

See also

append()

Definition at line 1077 of file qstring.h.

push_back() [2/2]

void QString::push_back ( QChar c )

inline

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.Appends the given ch character onto the end of this string.

Definition at line 1076 of file qstring.h.

push_front() [1/2]

void QString::push_front ( const QString & other )

inline

This function is provided for STL compatibility, prepending the given other string to the beginning of this string.

It is equivalent to prepend(other).

See also

prepend()

Definition at line 1079 of file qstring.h.

push_front() [2/2]

void QString::push_front ( QChar c )

inline

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.Prepends the given ch character to the beginning of this string.

Definition at line 1078 of file qstring.h.

QT_CORE_INLINE_SINCE() [1/2]

static QString static QString QString::QT_CORE_INLINE_SINCE ( 6 , 8  )

nodiscard

QT_CORE_INLINE_SINCE() [2/2]

QString::QT_CORE_INLINE_SINCE ( 6 , 8  )

nodiscard

rbegin() [1/2]

reverse_iterator QString::rbegin ( )

inline

Since

5.6

Returns a \l{STL-style iterators}{STL-style} reverse iterator pointing to the first character in the string, in reverse order.

iterator-invalidation-func-desc

See also

begin(), crbegin(), rend()

Definition at line 1061 of file qstring.h.

rbegin() [2/2]

const_reverse_iterator QString::rbegin ( ) const

inline

Since

5.6 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 1063 of file qstring.h.

remove() [1/4]

QString & QString::remove	(	const QString &	str,
		Qt::CaseSensitivity	cs = Qt::CaseSensitive )

Removes every occurrence of the given str string in this string, and returns a reference to this string.

{search-comparison-case-sensitivity} {search}

This is the same as replace(str, "", cs).

shrinking-erase

See also

replace()

Definition at line 3539 of file qstring.cpp.

remove() [2/4]

QString & QString::remove	(	QChar	ch,
		Qt::CaseSensitivity	cs = Qt::CaseSensitive )

Removes every occurrence of the character ch in this string, and returns a reference to this string.

{search-comparison-case-sensitivity} {search}

Example:

    QString t = "Ali Baba";
    t.remove(QChar('a'), Qt::CaseInsensitive);
    // t == "li Bb"

This is the same as replace(ch, "", cs).

shrinking-erase

See also

replace()

Definition at line 3619 of file qstring.cpp.

remove() [3/4]

QString & QString::remove	(	QLatin1StringView	str,
		Qt::CaseSensitivity	cs = Qt::CaseSensitive )

Since

5.11 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Removes every occurrence of the given Latin-1 string viewed by str from this string, and returns a reference to this string.

{search-comparison-case-sensitivity} {search}

This is the same as replace(str, "", cs).

shrinking-erase

See also

replace()

Definition at line 3564 of file qstring.cpp.

remove() [4/4]

QString & QString::remove	(	qsizetype	position,
		qsizetype	n )

Removes n characters from the string, starting at the given position index, and returns a reference to the string.

If the specified position index is within the string, but position + n is beyond the end of the string, the string is truncated at the specified position.

If n is <= 0 nothing is changed.

    QString s = "Montreal";
    s.remove(1, 4);
    // s == "Meal"

! [shrinking-erase] Element removal will preserve the string's capacity and not reduce the amount of allocated memory. To shed extra capacity and free as much memory as possible, call squeeze() after the last change to the string's size. ! [shrinking-erase]

See also

insert(), replace()

Definition at line 3458 of file qstring.cpp.

removeAt()

QString & QString::removeAt ( qsizetype pos )

inline

Since

6.5

Removes the character at index pos. If pos is out of bounds (i.e. pos >= size()), this function does nothing.

See also

remove()

Definition at line 636 of file qstring.h.

removeFirst()

QString & QString::removeFirst ( )

inline

Since

6.5

Removes the first character in this string. If the string is empty, this function does nothing.

See also

remove()

Definition at line 638 of file qstring.h.

removeIf()

template<typename Predicate>

QString & QString::removeIf ( Predicate pred )

inline

Since

6.1

Removes all elements for which the predicate pred returns true from the string. Returns a reference to the string.

See also

remove()

Definition at line 642 of file qstring.h.

removeLast()

QString & QString::removeLast ( )

inline

Since

6.5

Removes the last character in this string. If the string is empty, this function does nothing.

See also

remove()

Definition at line 639 of file qstring.h.

rend() [1/2]

reverse_iterator QString::rend ( )

inline

Since

5.6

Returns a \l{STL-style iterators}{STL-style} reverse iterator pointing just after the last character in the string, in reverse order.

iterator-invalidation-func-desc

See also

end(), crend(), rbegin()

Definition at line 1062 of file qstring.h.

rend() [2/2]

const_reverse_iterator QString::rend ( ) const

inline

Since

5.6 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 1064 of file qstring.h.

repeated()

QString QString::repeated ( qsizetype times ) const

nodiscard

Since

4.5

Returns a copy of this string repeated the specified number of times.

If times is less than 1, an empty string is returned.

Example:

QString str("ab");
str.repeated(4);            // returns "abababab"

Definition at line 8462 of file qstring.cpp.

replace() [1/11]

QString & QString::replace	(	const QChar *	before,
		qsizetype	blen,
		const QChar *	after,
		qsizetype	alen,
		Qt::CaseSensitivity	cs = Qt::CaseSensitive )

Definition at line 3863 of file qstring.cpp.

replace() [2/11]

QString & QString::replace	(	const QString &	before,
		const QString &	after,
		Qt::CaseSensitivity	cs = Qt::CaseSensitive )

Definition at line 3844 of file qstring.cpp.

replace() [3/11]

QString & QString::replace	(	const QString &	before,
		QLatin1StringView	after,
		Qt::CaseSensitivity	cs = Qt::CaseSensitive )

Definition at line 4049 of file qstring.cpp.

replace() [4/11]

QString & QString::replace	(	QChar	before,
		QChar	after,
		Qt::CaseSensitivity	cs = Qt::CaseSensitive )

Definition at line 3947 of file qstring.cpp.

replace() [5/11]

QString & QString::replace	(	QChar	c,
		const QString &	after,
		Qt::CaseSensitivity	cs = Qt::CaseSensitive )

Definition at line 3905 of file qstring.cpp.

replace() [6/11]

QString & QString::replace	(	QChar	c,
		QLatin1StringView	after,
		Qt::CaseSensitivity	cs = Qt::CaseSensitive )

Definition at line 4070 of file qstring.cpp.

replace() [7/11]

QString & QString::replace	(	QLatin1StringView	before,
		const QString &	after,
		Qt::CaseSensitivity	cs = Qt::CaseSensitive )

Definition at line 4026 of file qstring.cpp.

replace() [8/11]

QString & QString::replace	(	QLatin1StringView	before,
		QLatin1StringView	after,
		Qt::CaseSensitivity	cs = Qt::CaseSensitive )

Definition at line 4000 of file qstring.cpp.

replace() [9/11]

QString & QString::replace	(	qsizetype	i,
		qsizetype	len,
		const QChar *	s,
		qsizetype	slen )

Definition at line 3797 of file qstring.cpp.

replace() [10/11]

QString & QString::replace	(	qsizetype	position,
		qsizetype	n,
		const QString &	after )

Replaces n characters beginning at index position with the string after and returns a reference to this string.

Note

If the specified position index is within the string, but position + n goes outside the strings range, then n will be adjusted to stop at the end of the string.

Example:

    QString x = "Say yes!";
    QString y = "no";
    x.replace(4, 3, y);
    // x == "Say no!"

See also

insert(), remove()

Definition at line 3785 of file qstring.cpp.

replace() [11/11]

QString & QString::replace	(	qsizetype	i,
		qsizetype	len,
		QChar	after )

Definition at line 3816 of file qstring.cpp.

reserve()

void QString::reserve ( qsizetype size )

inline

Ensures the string has space for at least size characters.

If you know in advance how large a string will be, you can call this function to save repeated reallocation while building it. This can improve performance when building a string incrementally. A long sequence of operations that add to a string may trigger several reallocations, the last of which may leave you with significantly more space than you need. This is less efficient than doing a single allocation of the right size at the start.

If in doubt about how much space shall be needed, it is usually better to use an upper bound as size, or a high estimate of the most likely size, if a strict upper bound would be much bigger than this. If size is an underestimate, the string will grow as needed once the reserved size is exceeded, which may lead to a larger allocation than your best overestimate would have and will slow the operation that triggers it.

Warning

reserve() reserves memory but does not change the size of the string. Accessing data beyond the end of the string is undefined behavior. If you need to access memory beyond the current end of the string, use resize().

This function is useful for code that needs to build up a long string and wants to avoid repeated reallocation. In this example, we want to add to the string until some condition is true, and we're fairly sure that size is large enough to make a call to reserve() worthwhile:

    QString result;
    qsizetype maxSize;
    bool condition;
    QChar nextChar;
 
    result.reserve(maxSize);
 
    while (condition)
        result.append(nextChar);
 
    result.squeeze();

See also

squeeze(), capacity(), resize()

Definition at line 1447 of file qstring.h.

resize() [1/2]

void QString::resize

(

qsizetype

size

)

Sets the size of the string to size characters.

If size is greater than the current size, the string is extended to make it size characters long with the extra characters added to the end. The new characters are uninitialized.

If size is less than the current size, characters beyond position size are excluded from the string.

Note

While resize() will grow the capacity if needed, it never shrinks capacity. To shed excess capacity, use squeeze().

Example:

    QString s = "Hello world";
    s.resize(5);
    // s == "Hello"
 
    s.resize(8);
    // s == "Hello???" (where ? stands for any character)

If you want to append a certain number of identical characters to the string, use the \l {QString::}{resize(qsizetype, QChar)} overload.

If you want to expand the string so that it reaches a certain width and fill the new positions with a particular character, use the leftJustified() function:

If size is negative, it is equivalent to passing zero.

    QString r = "Hello";
    r = r.leftJustified(10, ' ');
    // r == "Hello     "

See also

truncate(), reserve(), squeeze()

Definition at line 2660 of file qstring.cpp.

resize() [2/2]

void QString::resize	(	qsizetype	newSize,
		QChar	fillChar )

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Since

5.7

Unlike \l {QString::}{resize(qsizetype)}, this overload initializes the new characters to fillChar:

    QString t = "Hello";
    r.resize(t.size() + 10, 'X');
    // t == "HelloXXXXXXXXXX"

Definition at line 2682 of file qstring.cpp.

resizeForOverwrite()

void QString::resizeForOverwrite

(

qsizetype

size

)

Since

6.8

Sets the size of the string to size characters. If the size of the string grows, the new characters are uninitialized.

The behavior is identical to {resize(size)}.

See also

resize()

Definition at line 2703 of file qstring.cpp.

right() [1/2]

QString QString::right ( qsizetype n ) &&

inlinenodiscard

Definition at line 460 of file qstring.h.

right() [2/2]

QString QString::right ( qsizetype n ) const &

inlinenodiscard

Definition at line 454 of file qstring.h.

rightJustified()

QString QString::rightJustified ( qsizetype width, QChar fill = u' ', bool truncate = false ) const

nodiscard

Returns a string of size() width that contains the fill character followed by the string.

For example:

    QString s = "apple";
    QString t = s.rightJustified(8, '.');    // t == "...apple"

If truncate is false and the size() of the string is more than width, then the returned string is a copy of the string.

If truncate is true and the size() of the string is more than width, then the resulting string is truncated at position width.

    QString str = "Pineapple";
    str = str.rightJustified(5, '.', true);    // str == "Pinea"

See also

leftJustified()

Definition at line 7145 of file qstring.cpp.

section() [1/2]

QString QString::section ( const QString & in_sep, qsizetype start, qsizetype end = -1, SectionFlags flags = SectionDefault ) const

nodiscard

Definition at line 5096 of file qstring.cpp.

section() [2/2]

QString QString::section ( QChar sep, qsizetype start, qsizetype end = -1, SectionFlags flags = SectionDefault ) const

inlinenodiscard

This function returns a section of the string.

This string is treated as a sequence of fields separated by the character, sep. The returned string consists of the fields from position start to position end inclusive. If end is not specified, all fields from position start to the end of the string are included. Fields are numbered 0, 1, 2, etc., counting from the left, and -1, -2, etc., counting from right to left.

The flags argument can be used to affect some aspects of the function's behavior, e.g. whether to be case sensitive, whether to skip empty fields and how to deal with leading and trailing separators; see \l{SectionFlags}.

    QString str;

If start or end is negative, we count fields from the right of the string, the right-most field being -1, the one from right-most field being -2, and so on.

    str = csv.section(',', -3, -2);  // str == "middlename,surname"
    str = path.section('/', -1); // str == "myapp"

See also

split()

Definition at line 1406 of file qstring.h.

setNum() [1/10]

QString & QString::setNum	(	double	n,
		char	format = 'g',
		int	precision = 6 )

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.Sets the string to the printed value of n, formatted according to the given format and precision, and returns a reference to the string.

See also

number(), QLocale::FloatingPointPrecisionOption, {Number Formats}

Definition at line 8113 of file qstring.cpp.

setNum() [2/10]

QString & QString::setNum ( float n, char format = 'g', int precision = 6 )

inline

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.Sets the string to the printed value of n, formatted according to the given format and precision, and returns a reference to the string.

The formatting always uses QLocale::C, i.e., English/UnitedStates. To get a localized string representation of a number, use QLocale::toString() with the appropriate locale.

See also

number()

Definition at line 1389 of file qstring.h.

setNum() [3/10]

QString & QString::setNum ( int n, int base = 10 )

inline

Sets the string to the printed value of n in the specified base, and returns a reference to the string.

The base is 10 by default and must be between 2 and 36.

    QString str;
    str.setNum(1234);       // str == "1234"

The formatting always uses QLocale::C, i.e., English/UnitedStates. To get a localized string representation of a number, use QLocale::toString() with the appropriate locale.

See also

number()

Definition at line 1381 of file qstring.h.

setNum() [4/10]

QString & QString::setNum ( long n, int base = 10 )

inline

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 1385 of file qstring.h.

setNum() [5/10]

QString & QString::setNum	(	qlonglong	n,
		int	base = 10 )

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 8081 of file qstring.cpp.

setNum() [6/10]

QString & QString::setNum	(	qulonglong	n,
		int	base = 10 )

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 8089 of file qstring.cpp.

setNum() [7/10]

QString & QString::setNum ( short n, int base = 10 )

inline

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 1377 of file qstring.h.

setNum() [8/10]

QString & QString::setNum ( uint n, int base = 10 )

inline

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 1383 of file qstring.h.

setNum() [9/10]

QString & QString::setNum ( ulong n, int base = 10 )

inline

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 1387 of file qstring.h.

setNum() [10/10]

QString & QString::setNum ( ushort n, int base = 10 )

inline

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Definition at line 1379 of file qstring.h.

setRawData()

QString & QString::setRawData	(	const QChar *	unicode,
		qsizetype	size )

Since

4.7

Resets the QString to use the first size Unicode characters in the array unicode. The data in unicode is not copied. The caller must be able to guarantee that unicode will not be deleted or modified as long as the QString (or an unmodified copy of it) exists.

This function can be used instead of fromRawData() to re-use existings QString objects to save memory re-allocations.

See also

fromRawData(), nullTerminate(), nullTerminated()

Definition at line 9446 of file qstring.cpp.

setUnicode() [1/2]

Q_WEAK_OVERLOAD QString & QString::setUnicode ( const char16_t * unicode, qsizetype size )

inline

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Since

6.9

See also

unicode(), setUtf16()

Definition at line 807 of file qstring.h.

setUnicode() [2/2]

QString & QString::setUnicode	(	const QChar *	unicode,
		qsizetype	size )

Resizes the string to size characters and copies unicode into the string.

If unicode is \nullptr, nothing is copied, but the string is still resized to size.

See also

unicode(), setUtf16()

Definition at line 6134 of file qstring.cpp.

setUtf16() [1/2]

QString & QString::setUtf16 ( const char16_t * unicode, qsizetype size )

inline

Since

6.9

Resizes the string to size characters and copies unicode into the string.

If unicode is \nullptr, nothing is copied, but the string is still resized to size.

Note that unlike fromUtf16(), this function does not consider BOMs and possibly differing byte ordering.

See also

utf16(), setUnicode()

Definition at line 809 of file qstring.h.

setUtf16() [2/2]

Q_WEAK_OVERLOAD QString & QString::setUtf16 ( const ushort * autf16, qsizetype asize )

inline

\obsolete Use the char16_t overload instead.

Definition at line 815 of file qstring.h.

shrink_to_fit()

void QString::shrink_to_fit ( )

inline

Since

5.10

This function is provided for STL compatibility. It is equivalent to squeeze().

See also

squeeze()

Definition at line 1080 of file qstring.h.

simplified() [1/2]

QString QString::simplified ( ) &&

inlinenodiscard

Definition at line 532 of file qstring.h.

simplified() [2/2]

QString QString::simplified ( ) const &

inlinenodiscard

Definition at line 530 of file qstring.h.

size()

qsizetype QString::size ( ) const

inlineconstexprnoexcept

Returns the number of characters in this string.

The last character in the string is at position size() - 1.

Example:

    QString str = "World";
    qsizetype n = str.size();   // n == 5
    str.data()[0];              // returns 'W'
    str.data()[4];              // returns 'd'

See also

isEmpty(), resize()

Definition at line 235 of file qstring.h.

slice() [1/2]

QString & QString::slice ( qsizetype pos )

inline

Since

6.8 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Modifies this string to start at position pos and extending to its end, and returns a reference to this string.

Note

The behavior is undefined if pos < 0 or pos > size().

See also

sliced(), first(), last(), chopped(), chop(), truncate()

Definition at line 257 of file qstring.h.

slice() [2/2]

QString & QString::slice ( qsizetype pos, qsizetype n )

inline

Since

6.8

Modifies this string to start at position pos, up to, but not including, the character (code point) at index position {pos + n}; and returns a reference to this string.

Note

The behavior is undefined if pos < 0, n < 0, or pos + n > size().

    QString x = u"Nine pineapples"_s;
    x.slice(5);     // x == "pineapples"
    x.slice(4, 3);  // x == "app"

See also

sliced(), first(), last(), chopped(), chop(), truncate()

Definition at line 259 of file qstring.h.

sliced() [1/4]

QString QString::sliced ( qsizetype pos ) &&

inlinenodiscard

Definition at line 488 of file qstring.h.

sliced() [2/4]

QString QString::sliced ( qsizetype pos ) const &

inlinenodiscard

Definition at line 473 of file qstring.h.

sliced() [3/4]

QString QString::sliced ( qsizetype pos, qsizetype n ) &&

inlinenodiscard

Definition at line 490 of file qstring.h.

sliced() [4/4]

QString QString::sliced ( qsizetype pos, qsizetype n ) const &

inlinenodiscard

Definition at line 475 of file qstring.h.

split() [1/3]

QStringList QString::split ( const QRegularExpression & sep, Qt::SplitBehavior behavior = Qt::KeepEmptyParts ) const

nodiscard

split() [2/3]

QStringList QString::split ( const QString & sep, Qt::SplitBehavior behavior = Qt::KeepEmptyParts, Qt::CaseSensitivity cs = Qt::CaseSensitive ) const

nodiscard

Splits the string into substrings wherever sep occurs, and returns the list of those strings.

If sep does not match anywhere in the string, split() returns a single-element list containing this string.

cs specifies whether sep should be matched case sensitively or case insensitively.

If behavior is Qt::SkipEmptyParts, empty entries don't appear in the result. By default, empty entries are kept.

Example:

    QString str = QStringLiteral("a,,b,c");
 
    QStringList list1 = str.split(u',');
    // list1: [ "a", "", "b", "c" ]
 
    QStringList list2 = str.split(u',', Qt::SkipEmptyParts);
    // list2: [ "a", "b", "c" ]

If sep is empty, split() returns an empty string, followed by each of the string's characters, followed by another empty string:

    QString str = "abc";
    auto parts = str.split(QString());
    // parts: {"", "a", "b", "c", ""}

To understand this behavior, recall that the empty string matches everywhere, so the above is qualitatively the same as:

    QString str = "/a/b/c/";
    auto parts = str.split(u'/');
    // parts: {"", "a", "b", "c", ""}

See also

QStringList::join(), section()

Since

5.14

Definition at line 8305 of file qstring.cpp.

split() [3/3]

QStringList QString::split ( QChar sep, Qt::SplitBehavior behavior = Qt::KeepEmptyParts, Qt::CaseSensitivity cs = Qt::CaseSensitive ) const

nodiscard

This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Since

5.14

Definition at line 8314 of file qstring.cpp.

squeeze()

void QString::squeeze ( )

inline

Releases any memory not required to store the character data.

The sole purpose of this function is to provide a means of fine tuning QString's memory usage. In general, you will rarely ever need to call this function.

See also

reserve(), capacity()

Definition at line 1455 of file qstring.h.

startsWith() [1/4]

bool QString::startsWith	(	const QString &	s,
		Qt::CaseSensitivity	cs = Qt::CaseSensitive ) const

Returns true if the string starts with s; otherwise returns false.

{search-comparison-case-sensitivity} {search}

    QString str = "Bananas";
    str.startsWith("Ban");     // returns true
    str.startsWith("Car");     // returns false

See also

endsWith()

Definition at line 5468 of file qstring.cpp.

startsWith() [2/4]

bool QString::startsWith	(	QChar	c,
		Qt::CaseSensitivity	cs = Qt::CaseSensitive ) const

Definition at line 5487 of file qstring.cpp.

startsWith() [3/4]

bool QString::startsWith	(	QLatin1StringView	s,
		Qt::CaseSensitivity	cs = Qt::CaseSensitive ) const

Definition at line 5476 of file qstring.cpp.

startsWith() [4/4]

bool QString::startsWith ( QStringView str, Qt::CaseSensitivity cs = Qt::CaseSensitive ) const

inlinenodiscardnoexcept

Since

5.10 This is an overloaded member function, provided for convenience. It differs from the above function only in what argument(s) it accepts.

Returns true if the string starts with the string view str; otherwise returns false.

{search-comparison-case-sensitivity} {search}

See also

endsWith()

Definition at line 496 of file qstring.h.

swap()

void QString::swap ( QString & other )

inlinenoexcept

Since

4.8 \memberswap{string}

Definition at line 228 of file qstring.h.

toCaseFolded() [1/2]

QString QString::toCaseFolded ( ) &&

inlinenodiscard

Definition at line 524 of file qstring.h.

toCaseFolded() [2/2]

QString QString::toCaseFolded ( ) const &

inlinenodiscard

Definition at line 522 of file qstring.h.

toDouble()

double QString::toDouble

(

bool *

ok = nullptr

)

const

Returns the string converted to a double value.

Returns an infinity if the conversion overflows or 0.0 if the conversion fails for other reasons (e.g. underflow).

If ok is not \nullptr, failure is reported by setting *{ok} to false, and success by setting *{ok} to true.

    QString str = "1234.56";
    double val = str.toDouble();   // val == 1234.56

Warning

The QString content may only contain valid numerical characters which includes the plus/minus sign, the character e used in scientific notation, and the decimal point. Including the unit or additional characters leads to a conversion error.

    bool ok;
    double d;
 
    d = QString( "1234.56e-02" ).toDouble(&ok); // ok == true, d == 12.3456
 
    d = QString( "1234.56e-02 Volt" ).toDouble(&ok); // ok == false, d == 0

The string conversion will always happen in the 'C' locale. For locale-dependent conversion use QLocale::toDouble()

    d = QString( "1234,56" ).toDouble(&ok); // ok == false
    d = QString( "1234.56" ).toDouble(&ok); // ok == true, d == 1234.56

For historical reasons, this function does not handle thousands group separators. If you need to convert such numbers, use QLocale::toDouble().

    d = QString( "1,234,567.89" ).toDouble(&ok); // ok == false
    d = QString( "1234567.89" ).toDouble(&ok); // ok == true

This function ignores leading and trailing whitespace.

See also

number(), QLocale::setDefault(), QLocale::toDouble(), trimmed()

Definition at line 7991 of file qstring.cpp.

toFloat()

float QString::toFloat

(

bool *

ok = nullptr

)

const

Returns the string converted to a float value.

Returns an infinity if the conversion overflows or 0.0 if the conversion fails for other reasons (e.g. underflow).

If ok is not \nullptr, failure is reported by setting *{ok} to false, and success by setting *{ok} to true.

Warning

The QString content may only contain valid numerical characters which includes the plus/minus sign, the character e used in scientific notation, and the decimal point. Including the unit or additional characters leads to a conversion error.

The string conversion will always happen in the 'C' locale. For locale-dependent conversion use QLocale::toFloat()

For historical reasons, this function does not handle thousands group separators. If you need to convert such numbers, use QLocale::toFloat().

Example:

    QString str1 = "1234.56";
    str1.toFloat();             // returns 1234.56
 
    bool ok;
    QString str2 = "R2D2";
    str2.toFloat(&ok);          // returns 0.0, sets ok to false
 
    QString str3 = "1234.56 Volt";
    str3.toFloat(&ok);          // returns 0.0, sets ok to false

This function ignores leading and trailing whitespace.

See also

number(), toDouble(), toInt(), QLocale::toFloat(), trimmed()

Definition at line 8037 of file qstring.cpp.

toHtmlEscaped()

QString QString::toHtmlEscaped ( ) const

nodiscard

Since

5.0

Converts a plain text string to an HTML string with HTML metacharacters {<}, {>}, {&}, and {"} replaced by HTML entities.

Example:

QString plain = "#include <QtCore>"
QString html = plain.toHtmlEscaped();
// html == "#include &lt;QtCore&gt;"

Definition at line 10119 of file qstring.cpp.

toInt()

int QString::toInt ( bool * ok = nullptr, int base = 10 ) const

inline

Returns the string converted to an int using base base, which is 10 by default and must be between 2 and 36, or 0.

Returns 0 if the conversion fails.

If ok is not \nullptr, failure is reported by setting *{ok} to false, and success by setting *{ok} to true.

If base is 0, the C language convention is used: if the string begins with "0x", base 16 is used; otherwise, if the string begins with "0b", base 2 is used; otherwise, if the string begins with "0", base 8 is used; otherwise, base 10 is used.

The string conversion will always happen in the 'C' locale. For locale-dependent conversion use QLocale::toInt()

Example:

    QString str = "FF";
    bool ok;
    int hex = str.toInt(&ok, 16);       // hex == 255, ok == true
    int dec = str.toInt(&ok, 10);       // dec == 0, ok == false

This function ignores leading and trailing whitespace.

Note

Support for the "0b" prefix was added in Qt 6.4.

See also

number(), toUInt(), toDouble(), QLocale::toInt()

Definition at line 850 of file qstring.h.

tokenize() [1/3]

template<typename Needle, typename... Flags>

auto QString::tokenize ( Needle && needle, Flags... flags ) && -> decltype(qTokenize(std::move(*this), std::forward<Needle>(needle), flags...))

inlinenodiscardnoexcept

Definition at line 692 of file qstring.h.

tokenize() [2/3]

template<typename Needle, typename... Flags>

auto QString::tokenize ( Needle && needle, Flags... flags ) const && -> decltype(qTokenize(std::move(*this), std::forward<Needle>(needle), flags...))

inlinenodiscardnoexcept

Definition at line 686 of file qstring.h.

tokenize() [3/3]

template<typename Needle, typename... Flags>

auto QString::tokenize ( Needle && needle, Flags... flags ) const & -> decltype(qTokenize(*this, std::forward<Needle>(needle), flags...))

inlinenodiscardnoexcept

Definition at line 680 of file qstring.h.

toLatin1() [1/2]

QByteArray QString::toLatin1 ( ) &&

inlinenodiscard

Definition at line 736 of file qstring.h.

toLatin1() [2/2]

QByteArray QString::toLatin1 ( ) const &

inlinenodiscard

Definition at line 734 of file qstring.h.

toLocal8Bit() [1/2]

QByteArray QString::toLocal8Bit ( ) &&

inlinenodiscard

Definition at line 744 of file qstring.h.

toLocal8Bit() [2/2]

QByteArray QString::toLocal8Bit ( ) const &

inlinenodiscard

Definition at line 742 of file qstring.h.

toLong()

long QString::toLong ( bool * ok = nullptr, int base = 10 ) const

inline

Returns the string converted to a long using base base, which is 10 by default and must be between 2 and 36, or 0.

Returns 0 if the conversion fails.

If ok is not \nullptr, failure is reported by setting *{ok} to false, and success by setting *{ok} to true.

If base is 0, the C language convention is used: if the string begins with "0x", base 16 is used; otherwise, if the string begins with "0b", base 2 is used; otherwise, if the string begins with "0", base 8 is used; otherwise, base 10 is used.

The string conversion will always happen in the 'C' locale. For locale-dependent conversion use QLocale::toLongLong()

Example:

    QString str = "FF";
    bool ok;
 
    long hex = str.toLong(&ok, 16);     // hex == 255, ok == true
    long dec = str.toLong(&ok, 10);     // dec == 0, ok == false

This function ignores leading and trailing whitespace.

Note

Support for the "0b" prefix was added in Qt 6.4.

See also

number(), toULong(), toInt(), QLocale::toInt()

Definition at line 854 of file qstring.h.

toLongLong()

qlonglong QString::toLongLong	(	bool *	ok = nullptr,
		int	base = 10 ) const

Returns the string converted to a {long long} using base base, which is 10 by default and must be between 2 and 36, or 0.

Returns 0 if the conversion fails.

If ok is not \nullptr, failure is reported by setting *{ok} to false, and success by setting *{ok} to true.

If base is 0, the C language convention is used: if the string begins with "0x", base 16 is used; otherwise, if the string begins with "0b", base 2 is used; otherwise, if the string begins with "0", base 8 is used; otherwise, base 10 is used.

The string conversion will always happen in the 'C' locale. For locale-dependent conversion use QLocale::toLongLong()

Example:

    QString str = "FF";
    bool ok;
 
    qint64 hex = str.toLongLong(&ok, 16);      // hex == 255, ok == true
    qint64 dec = str.toLongLong(&ok, 10);      // dec == 0, ok == false

This function ignores leading and trailing whitespace.

Note

Support for the "0b" prefix was added in Qt 6.4.

See also

number(), toULongLong(), toInt(), QLocale::toLongLong()

toLower() [1/2]

QString QString::toLower ( ) &&

inlinenodiscard

Definition at line 516 of file qstring.h.

toLower() [2/2]

QString QString::toLower ( ) const &

inlinenodiscard

Definition at line 514 of file qstring.h.

toShort()

short QString::toShort ( bool * ok = nullptr, int base = 10 ) const

inline

Returns the string converted to a short using base base, which is 10 by default and must be between 2 and 36, or 0.

Returns 0 if the conversion fails.

If ok is not \nullptr, failure is reported by setting *{ok} to false, and success by setting *{ok} to true.

If base is 0, the C language convention is used: if the string begins with "0x", base 16 is used; otherwise, if the string begins with "0b", base 2 is used; otherwise, if the string begins with "0", base 8 is used; otherwise, base 10 is used.

The string conversion will always happen in the 'C' locale. For locale-dependent conversion use QLocale::toShort()

Example:

    QString str = "FF";
    bool ok;
 
    short hex = str.toShort(&ok, 16);   // hex == 255, ok == true
    short dec = str.toShort(&ok, 10);   // dec == 0, ok == false

This function ignores leading and trailing whitespace.

Note

Support for the "0b" prefix was added in Qt 6.4.

See also

number(), toUShort(), toInt(), QLocale::toShort()

Definition at line 846 of file qstring.h.

toStdString()

std::string QString::toStdString

(

)

const

Returns a std::string object with the data contained in this QString.

The Unicode data is converted into 8-bit characters using the toUtf8() function.

This method is mostly useful to pass a QString to a function that accepts a std::string object.

See also

toLatin1(), toUtf8(), toLocal8Bit(), QByteArray::toStdString()

Definition at line 9376 of file qstring.cpp.

toStdU16String()

std::u16string QString::toStdU16String ( ) const

inline

Since

5.5

Returns a std::u16string object with the data contained in this QString. The Unicode data is the same as returned by the utf16() method.

See also

utf16(), toStdWString(), toStdU32String()

Definition at line 1593 of file qstring.h.

toStdU32String()

std::u32string QString::toStdU32String ( ) const

inline

Since

5.5

Returns a std::u32string object with the data contained in this QString. The Unicode data is the same as returned by the toUcs4() method.

See also

toUcs4(), toStdWString(), toStdU16String()

Definition at line 1599 of file qstring.h.

toStdWString()

std::wstring QString::toStdWString ( ) const

inline

Returns a std::wstring object with the data contained in this QString.

The std::wstring is encoded in UTF-16 on platforms where wchar_t is 2 bytes wide (for example, Windows) and in UTF-32 on platforms where wchar_t is 4 bytes wide (most Unix systems).

This method is mostly useful to pass a QString to a function that accepts a std::wstring object.

See also

utf16(), toLatin1(), toUtf8(), toLocal8Bit(), toStdU16String(), toStdU32String()

Definition at line 1579 of file qstring.h.

toUcs4()

QList< uint > QString::toUcs4 ( ) const

nodiscard

Since

4.2

Returns a UCS-4/UTF-32 representation of the string as a QList<uint>.

UTF-32 is a Unicode codec and therefore it is lossless. All characters from this string will be encoded in UTF-32. Any invalid sequence of code units in this string is replaced by the Unicode replacement character (QChar::ReplacementCharacter, which corresponds to {U+FFFD}).

The returned list is not 0-terminated.

See also

fromUtf8(), toUtf8(), toLatin1(), toLocal8Bit(), QStringEncoder, fromUcs4(), toWCharArray()

Definition at line 5856 of file qstring.cpp.

toUInt()

uint QString::toUInt ( bool * ok = nullptr, int base = 10 ) const

inline

Returns the string converted to an {unsigned int} using base base, which is 10 by default and must be between 2 and 36, or 0.

Returns 0 if the conversion fails.

If ok is not \nullptr, failure is reported by setting *{ok} to false, and success by setting *{ok} to true.

If base is 0, the C language convention is used: if the string begins with "0x", base 16 is used; otherwise, if the string begins with "0b", base 2 is used; otherwise, if the string begins with "0", base 8 is used; otherwise, base 10 is used.

The string conversion will always happen in the 'C' locale. For locale-dependent conversion use QLocale::toUInt()

Example:

    QString str = "FF";
    bool ok;
 
    uint hex = str.toUInt(&ok, 16);     // hex == 255, ok == true
    uint dec = str.toUInt(&ok, 10);     // dec == 0, ok == false

This function ignores leading and trailing whitespace.

Note

Support for the "0b" prefix was added in Qt 6.4.

See also

number(), toInt(), QLocale::toUInt()

Definition at line 852 of file qstring.h.

toULong()

ulong QString::toULong ( bool * ok = nullptr, int base = 10 ) const

inline

Returns the string converted to an {unsigned long} using base base, which is 10 by default and must be between 2 and 36, or 0.

Returns 0 if the conversion fails.

If ok is not \nullptr, failure is reported by setting *{ok} to false, and success by setting *{ok} to true.

If base is 0, the C language convention is used: if the string begins with "0x", base 16 is used; otherwise, if the string begins with "0b", base 2 is used; otherwise, if the string begins with "0", base 8 is used; otherwise, base 10 is used.

The string conversion will always happen in the 'C' locale. For locale-dependent conversion use QLocale::toULongLong()

Example:

    QString str = "FF";
    bool ok;
 
    ulong hex = str.toULong(&ok, 16);   // hex == 255, ok == true
    ulong dec = str.toULong(&ok, 10);   // dec == 0, ok == false

This function ignores leading and trailing whitespace.

Note

Support for the "0b" prefix was added in Qt 6.4.

See also

number(), QLocale::toUInt()

Definition at line 856 of file qstring.h.

toULongLong()

qulonglong QString::toULongLong	(	bool *	ok = nullptr,
		int	base = 10 ) const

Returns the string converted to an {unsigned long long} using base base, which is 10 by default and must be between 2 and 36, or 0.

Returns 0 if the conversion fails.

If ok is not \nullptr, failure is reported by setting *{ok} to false, and success by setting *{ok} to true.

If base is 0, the C language convention is used: if the string begins with "0x", base 16 is used; otherwise, if the string begins with "0b", base 2 is used; otherwise, if the string begins with "0", base 8 is used; otherwise, base 10 is used.

The string conversion will always happen in the 'C' locale. For locale-dependent conversion use QLocale::toULongLong()

Example:

    QString str = "FF";
    bool ok;
 
    quint64 hex = str.toULongLong(&ok, 16);    // hex == 255, ok == true
    quint64 dec = str.toULongLong(&ok, 10);    // dec == 0, ok == false

This function ignores leading and trailing whitespace.

Note

Support for the "0b" prefix was added in Qt 6.4.

See also

number(), toLongLong(), QLocale::toULongLong()

toUpper() [1/2]

QString QString::toUpper ( ) &&

inlinenodiscard

Definition at line 520 of file qstring.h.

toUpper() [2/2]

QString QString::toUpper ( ) const &

inlinenodiscard

Definition at line 518 of file qstring.h.

toUShort()

ushort QString::toUShort ( bool * ok = nullptr, int base = 10 ) const

inline

Returns the string converted to an {unsigned short} using base base, which is 10 by default and must be between 2 and 36, or 0.

Returns 0 if the conversion fails.

If ok is not \nullptr, failure is reported by setting *{ok} to false, and success by setting *{ok} to true.

If base is 0, the C language convention is used: if the string begins with "0x", base 16 is used; otherwise, if the string begins with "0b", base 2 is used; otherwise, if the string begins with "0", base 8 is used; otherwise, base 10 is used.

The string conversion will always happen in the 'C' locale. For locale-dependent conversion use QLocale::toUShort()

Example:

    QString str = "FF";
    bool ok;
 
    ushort hex = str.toUShort(&ok, 16);     // hex == 255, ok == true
    ushort dec = str.toUShort(&ok, 10);     // dec == 0, ok == false

This function ignores leading and trailing whitespace.

Note

Support for the "0b" prefix was added in Qt 6.4.

See also

number(), toShort(), QLocale::toUShort()

Definition at line 848 of file qstring.h.

toUtf8() [1/2]

QByteArray QString::toUtf8 ( ) &&

inlinenodiscard

Definition at line 740 of file qstring.h.

toUtf8() [2/2]

QByteArray QString::toUtf8 ( ) const &

inlinenodiscard

Definition at line 738 of file qstring.h.

toWCharArray()

QT_WARNING_PUSH qsizetype QString::toWCharArray ( wchar_t * array ) const

inline

Since

4.2

Fills the array with the data contained in this QString object. The array is encoded in UTF-16 on platforms where wchar_t is 2 bytes wide (e.g. windows) and in UTF-32 on platforms where wchar_t is 4 bytes wide (most Unix systems).

array has to be allocated by the caller and contain enough space to hold the complete string (allocating the array with the same length as the string is always sufficient).

This function returns the actual length of the string in array.

Note

This function does not append a null character to the array.

See also

utf16(), toUcs4(), toLatin1(), toUtf8(), toLocal8Bit(), toStdWString(), QStringView::toWCharArray()

Definition at line 1413 of file qstring.h.

trimmed() [1/2]

QString QString::trimmed ( ) &&

inlinenodiscard

Definition at line 528 of file qstring.h.

trimmed() [2/2]

QString QString::trimmed ( ) const &

inlinenodiscard

Definition at line 526 of file qstring.h.

truncate()

void QString::truncate

(

qsizetype

position

)

Truncates the string starting from, and including, the element at index position.

If the specified position index is beyond the end of the string, nothing happens.

Example:

    QString str = "Vladivostok";
    str.truncate(4);
    // str == "Vlad"

If position is negative, it is equivalent to passing zero.

See also

chop(), resize(), first(), QStringView::truncate()

Definition at line 6368 of file qstring.cpp.

unicode()

const QChar * QString::unicode ( ) const

inline

Returns a Unicode representation of the string.

The result remains valid until the string is modified.

Note

The returned string may not be '\0'-terminated. Use size() to determine the length of the array.

See also

utf16(), fromRawData()

Definition at line 1350 of file qstring.h.

utf16()

const ushort * QString::utf16

(

)

const

Returns the QString as a '\0\'-terminated array of unsigned shorts.

The result remains valid until the string is modified.

The returned string is in host byte order.

See also

unicode()

Definition at line 7054 of file qstring.cpp.

vasprintf()

QString QString::vasprintf ( const char * cformat, va_list ap )

static

Since

5.5

Equivalent method to asprintf(), but takes a va_list ap instead a list of variable arguments. See the asprintf() documentation for an explanation of cformat.

This method does not call the va_end macro, the caller is responsible to call va_end on ap.

See also

asprintf()

Definition at line 7444 of file qstring.cpp.

Friends And Related Symbol Documentation

::tst_QString

friend class ::tst_QString

friend

Definition at line 144 of file qstring.h.

comparesEqual [1/9]

bool comparesEqual ( const QString & lhs, const char * rhs )

friend

Definition at line 1035 of file qstring.h.

comparesEqual [2/9]

bool comparesEqual ( const QString & lhs, const QByteArray & rhs )

friend

Definition at line 1026 of file qstring.h.

comparesEqual [3/9]

bool comparesEqual ( const QString & lhs, QByteArrayView rhs )

friend

Definition at line 1012 of file qstring.h.

comparesEqual [4/9]

bool comparesEqual ( const QString & lhs, QChar rhs )

friend

Definition at line 933 of file qstring.h.

comparesEqual [5/9]

bool comparesEqual ( const QString & s1, const char16_t * s2 )

friend

Definition at line 926 of file qstring.h.

comparesEqual [6/9]

bool comparesEqual ( const QString & s1, const QString & s2 )

friend

Definition at line 884 of file qstring.h.

comparesEqual [7/9]

bool comparesEqual ( const QString & s1, QLatin1StringView s2 )

friend

Definition at line 909 of file qstring.h.

comparesEqual [8/9]

Q_WEAK_OVERLOAD friend bool comparesEqual ( const QString & s1, QUtf8StringView s2 )

friend

Definition at line 891 of file qstring.h.

comparesEqual [9/9]

bool comparesEqual ( const QString & s1, std::nullptr_t  )

friend

Definition at line 920 of file qstring.h.

compareThreeWay [1/9]

Qt::strong_ordering compareThreeWay ( const QString & lhs, const char * rhs )

friend

Definition at line 1038 of file qstring.h.

compareThreeWay [2/9]

Qt::strong_ordering compareThreeWay ( const QString & lhs, const QByteArray & rhs )

friend

Definition at line 1029 of file qstring.h.

compareThreeWay [3/9]

Qt::strong_ordering compareThreeWay ( const QString & lhs, QByteArrayView rhs )

friend

Definition at line 1018 of file qstring.h.

compareThreeWay [4/9]

Qt::strong_ordering compareThreeWay ( const QString & lhs, QChar rhs )

friend

Definition at line 935 of file qstring.h.

compareThreeWay [5/9]

Qt::strong_ordering compareThreeWay ( const QString & s1, const char16_t * s2 )

friend

Definition at line 928 of file qstring.h.

compareThreeWay [6/9]

Qt::strong_ordering compareThreeWay ( const QString & s1, const QString & s2 )

friend

Definition at line 886 of file qstring.h.

compareThreeWay [7/9]

Qt::strong_ordering compareThreeWay ( const QString & s1, QLatin1StringView s2 )

friend

Definition at line 912 of file qstring.h.

compareThreeWay [8/9]

Q_WEAK_OVERLOAD friend Qt::strong_ordering compareThreeWay ( const QString & s1, QUtf8StringView s2 )

friend

Definition at line 894 of file qstring.h.

compareThreeWay [9/9]

Qt::strong_ordering compareThreeWay ( const QString & s1, std::nullptr_t  )

friend

Definition at line 922 of file qstring.h.

erase

template<typename T>

qsizetype erase ( QString & s, const T & t )

friend

Since

6.1

Removes all elements that compare equal to t from the string s. Returns the number of elements removed, if any.

See also

erase_if

Definition at line 1755 of file qstring.h.

erase_if

template<typename Predicate>

qsizetype erase_if ( QString & s, Predicate pred )

friend

Since

6.1

Removes all elements for which the predicate pred returns true from the string s. Returns the number of elements removed, if any.

See also

erase

Definition at line 1761 of file qstring.h.

operator""_s()

operator""_s ( const char16_t * str, size_t size )

related

\macro QStringLiteral(str)

The macro generates the data for a QString out of the string literal str at compile time. Creating a QString from it is free in this case, and the generated string data is stored in the read-only segment of the compiled object file.

If you have code that looks like this:

// hasAttribute takes a QString argument
if (node.hasAttribute("http-contents-length")) //...

then a temporary QString will be created to be passed as the {hasAttribute} function parameter. This can be quite expensive, as it involves a memory allocation and the copy/conversion of the data into QString's internal encoding.

This cost can be avoided by using QStringLiteral instead:

if (node.hasAttribute(QStringLiteral(u"http-contents-length"))) //...

In this case, QString's internal data will be generated at compile time; no conversion or allocation will occur at runtime.

Using QStringLiteral instead of a double quoted plain C++ string literal can significantly speed up creation of QString instances from data known at compile time.

Note

QLatin1StringView can still be more efficient than QStringLiteral when the string is passed to a function that has an overload taking QLatin1StringView and this overload avoids conversion to QString. For instance, QString::operator==() can compare to a QLatin1StringView directly:

if (attribute.name() == "http-contents-length"_L1) //...

Note

Some compilers have bugs encoding strings containing characters outside the US-ASCII character set. Make sure you prefix your string with {u} in those cases. It is optional otherwise.

See also

QByteArrayLiteral

Since

6.4

Literal operator that creates a QString out of the first size characters in the char16_t string literal str.

The QString is created at compile time, and the generated string data is stored in the read-only segment of the compiled object file. Duplicate literals may share the same read-only memory. This functionality is interchangeable with QStringLiteral, but saves typing when many string literals are present in the code.

The following code creates a QString:

using namespace Qt::Literals::StringLiterals;
 
auto str = u"hello"_s;

See also

Qt::Literals::StringLiterals

Definition at line 1769 of file qstring.h.

operator+() [1/4]

QString operator+ ( const char * s1, const QString & s2 )

related

Returns a string which is the result of concatenating s1 and s2 (s1 is converted to Unicode using the QString::fromUtf8() function).

See also

QString::fromUtf8()

Definition at line 1565 of file qstring.h.

operator+() [2/4]

QString operator+ ( const QString & lhs, QStringView rhs )

related

Since

6.9

Returns a string that is the result of concatenating lhs and rhs.

Definition at line 1549 of file qstring.h.

operator+() [3/4]

QString operator+ ( const QString & s1, const char * s2 )

related

Returns a string which is the result of concatenating s1 and s2 (s2 is converted to Unicode using the QString::fromUtf8() function).

See also

QString::fromUtf8()

Definition at line 1561 of file qstring.h.

operator+() [4/4]

QString operator+ ( QString && s1, const QString & s2 )

related

Returns a string which is the result of concatenating s1 and s2.

Definition at line 1541 of file qstring.h.

operator<<()

QDataStream & operator<< ( QDataStream & stream, const QString & string )

related

Writes the given string to the specified stream.

See also

{Serializing Qt Data Types}

operator>>()

QDataStream & operator>> ( QDataStream & stream, QString & string )

related

Reads a string from the specified stream into the given string.

See also

{Serializing Qt Data Types}

QAbstractConcatenable

friend struct QAbstractConcatenable

friend

Definition at line 1183 of file qstring.h.

QByteArray

friend class QByteArray

friend

Definition at line 1182 of file qstring.h.

QStringView

friend class QStringView

friend

Definition at line 1181 of file qstring.h.

Member Data Documentation

cs [1/2]

QString static QString qsizetype Qt::CaseSensitivity QString::cs = Qt::CaseSensitive) const

Definition at line 370 of file qstring.h.

cs [2/2]

qsizetype Qt::CaseSensitivity QString::cs = Qt::CaseSensitive) const

Definition at line 378 of file qstring.h.

from [1/2]

QString static QString qsizetype QString::from = 0

Definition at line 370 of file qstring.h.

from [2/2]

qsizetype QString::from

Definition at line 378 of file qstring.h.

---

The documentation for this class was generated from the following files:

• qtbase/src/corelib/text/qstring.h (3b73bc463db1407096941239170040a2692ecdac)
• qtbase/src/corelib/text/qstringconverter.h (8df072fc8006510c9b743e8ffedaaf51a876883a)
• qtbase/src/corelib/text/qstring.cpp (d1539331dd813c83916a323f6cdc7fd6aacb0043)