src_corelib_text_qregularexpression.cpp

Go to the documentation of this file.

// Copyright (C) 2016 Giuseppe D'Angelo <dangelog@gmail.com>.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
 
#include <QString>
#include <QStringList>
#include <QRegularExpression>
#include <QRegularExpressionMatch>
#include <QRegularExpressionMatchIterator>
 
int main() {
 
    {
        //! [0]
        QRegularExpression re("a pattern");
        //! [0]
    }
 
    {
        //! [1]
        QRegularExpression re;
        re.setPattern("another pattern");
        //! [1]
    }
 
    {
        //! [2]
        // matches two digits followed by a space and a word
        QRegularExpression re("\\d\\d \\w+");
 
        // matches a backslash
        QRegularExpression re2("\\\\");
        //! [2]
    }
 
    {
        //! [3]
        QRegularExpression re("a third pattern");
        QString pattern = re.pattern(); // pattern == "a third pattern"
        //! [3]
    }
 
    {
        //! [4]
        // matches "Qt rocks", but also "QT rocks", "QT ROCKS", "qT rOcKs", etc.
        QRegularExpression re("Qt rocks", QRegularExpression::CaseInsensitiveOption);
        //! [4]
    }
 
    {
        //! [5]
        QRegularExpression re("^\\d+$");
        re.setPatternOptions(QRegularExpression::MultilineOption);
        // re matches any line in the subject string that contains only digits (but at least one)
        //! [5]
    }
 
    {
        //! [6]
        QRegularExpression re = QRegularExpression("^two.*words$", QRegularExpression::MultilineOption
                                                                | QRegularExpression::DotMatchesEverythingOption);
 
        QRegularExpression::PatternOptions options = re.patternOptions();
        // options == QRegularExpression::MultilineOption | QRegularExpression::DotMatchesEverythingOption
        //! [6]
    }
 
    {
        //! [7]
        // match two digits followed by a space and a word
        QRegularExpression re("\\d\\d \\w+");
        QRegularExpressionMatch match = re.match("abc123 def");
        bool hasMatch = match.hasMatch(); // true
        //! [7]
    }
 
    {
        //! [8]
        QRegularExpression re("\\d\\d \\w+");
        QRegularExpressionMatch match = re.match("abc123 def");
        if (match.hasMatch()) {
            QString matched = match.captured(0); // matched == "23 def"
            // ...
        }
        //! [8]
    }
 
    {
        //! [9]
        QRegularExpression re("\\d\\d \\w+");
        QRegularExpressionMatch match = re.match("12 abc 45 def", 1);
        if (match.hasMatch()) {
            QString matched = match.captured(0); // matched == "45 def"
            // ...
        }
        //! [9]
    }
 
    {
        //! [10]
        QRegularExpression re("^(\\d\\d)/(\\d\\d)/(\\d\\d\\d\\d)$");
        QRegularExpressionMatch match = re.match("08/12/1985");
        if (match.hasMatch()) {
            QString day = match.captured(1); // day == "08"
            QString month = match.captured(2); // month == "12"
            QString year = match.captured(3); // year == "1985"
            // ...
        }
        //! [10]
    }
 
    {
        //! [11]
        QRegularExpression re("abc(\\d+)def");
        QRegularExpressionMatch match = re.match("XYZabc123defXYZ");
        if (match.hasMatch()) {
            int startOffset = match.capturedStart(1); // startOffset == 6
            int endOffset = match.capturedEnd(1); // endOffset == 9
            // ...
        }
        //! [11]
    }
 
    {
        //! [12]
        QRegularExpression re("^(?<date>\\d\\d)/(?<month>\\d\\d)/(?<year>\\d\\d\\d\\d)$");
        QRegularExpressionMatch match = re.match("08/12/1985");
        if (match.hasMatch()) {
            QString date = match.captured("date"); // date == "08"
            QString month = match.captured("month"); // month == "12"
            QString year = match.captured("year"); // year == 1985
        }
        //! [12]
    }
 
    {
        //! [13]
        QRegularExpression re("(\\w+)");
        QRegularExpressionMatchIterator i = re.globalMatch("the quick fox");
        //! [13]
 
        //! [14]
        QStringList words;
        while (i.hasNext()) {
            QRegularExpressionMatch match = i.next();
            QString word = match.captured(1);
            words << word;
        }
        // words contains "the", "quick", "fox"
        //! [14]
    }
 
    {
        //! [15]
        QString pattern("^(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec) \\d\\d?, \\d\\d\\d\\d$");
        QRegularExpression re(pattern);
 
        QString input("Jan 21,");
        QRegularExpressionMatch match = re.match(input, 0, QRegularExpression::PartialPreferCompleteMatch);
        bool hasMatch = match.hasMatch(); // false
        bool hasPartialMatch = match.hasPartialMatch(); // true
        //! [15]
    }
 
    {
        QString pattern("^(Jan|Feb|Mar|Apr|May|Jun|Jul|Aug|Sep|Oct|Nov|Dec) \\d\\d?, \\d\\d\\d\\d$");
        QRegularExpression re(pattern);
        //! [16]
        QString input("Dec 8, 1985");
        QRegularExpressionMatch match = re.match(input, 0, QRegularExpression::PartialPreferCompleteMatch);
        bool hasMatch = match.hasMatch(); // true
        bool hasPartialMatch = match.hasPartialMatch(); // false
        //! [16]
    }
 
    {
        //! [17]
        QRegularExpression re("abc\\w+X|def");
        QRegularExpressionMatch match = re.match("abcdef", 0, QRegularExpression::PartialPreferCompleteMatch);
        bool hasMatch = match.hasMatch(); // true
        bool hasPartialMatch = match.hasPartialMatch(); // false
        QString captured = match.captured(0); // captured == "def"
        //! [17]
    }
 
    {
        //! [18]
        QRegularExpression re("abc\\w+X|defY");
        QRegularExpressionMatch match = re.match("abcdef", 0, QRegularExpression::PartialPreferCompleteMatch);
        bool hasMatch = match.hasMatch(); // false
        bool hasPartialMatch = match.hasPartialMatch(); // true
        QString captured = match.captured(0); // captured == "abcdef"
        //! [18]
    }
 
    {
        //! [19]
        QRegularExpression re("abc|ab");
        QRegularExpressionMatch match = re.match("ab", 0, QRegularExpression::PartialPreferFirstMatch);
        bool hasMatch = match.hasMatch(); // false
        bool hasPartialMatch = match.hasPartialMatch(); // true
        //! [19]
    }
 
    {
        //! [20]
        QRegularExpression re("abc(def)?");
        QRegularExpressionMatch match = re.match("abc", 0, QRegularExpression::PartialPreferFirstMatch);
        bool hasMatch = match.hasMatch(); // false
        bool hasPartialMatch = match.hasPartialMatch(); // true
        //! [20]
    }
 
    {
        //! [21]
        QRegularExpression re("(abc)*");
        QRegularExpressionMatch match = re.match("abc", 0, QRegularExpression::PartialPreferFirstMatch);
        bool hasMatch = match.hasMatch(); // false
        bool hasPartialMatch = match.hasPartialMatch(); // true
        //! [21]
    }
 
    {
        //! [22]
        QRegularExpression invalidRe("(unmatched|parenthesis");
        bool isValid = invalidRe.isValid(); // false
        //! [22]
    }
 
    {
        //! [23]
        QRegularExpression invalidRe("(unmatched|parenthesis");
        if (!invalidRe.isValid()) {
            QString errorString = invalidRe.errorString(); // errorString == "missing )"
            int errorOffset = invalidRe.patternErrorOffset(); // errorOffset == 22
            // ...
        }
        //! [23]
    }
 
    {
        //! [26]
        QString escaped = QRegularExpression::escape("a(x) = f(x) + g(x)");
        // escaped == "a\\‍(x\\‍)\\ \\=\\ f\\‍(x\\‍)\\ \\+\\ g\\‍(x\\‍)"
        //! [26]
    }
 
    {
        QString name;
        QString nickname;
        //! [27]
        QString pattern = "(" + QRegularExpression::escape(name) +
                        "|" + QRegularExpression::escape(nickname) + ")";
        QRegularExpression re(pattern);
        //! [27]
    }
 
    {
        QString string;
        QRegularExpression re;
        //! [28]
        QRegularExpressionMatch match = re.match(string);
        for (int i = 0; i <= match.lastCapturedIndex(); ++i) {
            QString captured = match.captured(i);
            // ...
        }
        //! [28]
    }
 
    {
        //! [29]
        QRegularExpression re("(\\d\\d) (?<name>\\w+)");
        QRegularExpressionMatch match = re.match("23 Jordan");
        if (match.hasMatch()) {
            QString number = match.captured(1); // first == "23"
            QString name = match.captured("name"); // name == "Jordan"
        }
        //! [29]
    }
 
    {
        //! [30]
        // extracts the words
        QRegularExpression re("(\\w+)");
        QString subject("the quick fox");
        QRegularExpressionMatchIterator i = re.globalMatch(subject);
        while (i.hasNext()) {
            QRegularExpressionMatch match = i.next();
            // ...
        }
        //! [30]
    }
 
    {
        //! [31]
        QString wildcard = QRegularExpression::wildcardToRegularExpression("*.jpeg");
        // Will match files with names like:
        //    foo.jpeg
        //    f_o_o.jpeg
        //    föö.jpeg
        //! [31]
    }
 
#if 0
    //! [32]
        (?<day>\d\d)-(?<month>\d\d)-(?<year>\d\d\d\d) (\w+) (?<name>\w+)
    //! [32]
 
    //! [33]
        ("", "day", "month", "year", "", "name")
    //! [33]
#endif
 
    {
        //! [34]
        // using a raw string literal, R"(raw_characters)", to be able to use "\w"
        // without having to escape the backslash as "\\w"
        QRegularExpression re(R"(\w+)");
        QString subject("the quick fox");
        for (const QRegularExpressionMatch &match : re.globalMatch(subject)) {
            // ...
        }
        //! [34]
    }
 
    {
        //! [35]
        // matches two digits followed by a space and a word
        QRegularExpression re(R"(\d\d \w+)");
        //! [35]
    }
 
    {
        //! [36]
        QRegularExpression re("([a-z]+)|([A-Z]+)");
        QRegularExpressionMatch m = re.match("UPPERCASE");
        if (m.hasMatch()) {
            qDebug() << m.hasCaptured(0); // true
            qDebug() << m.hasCaptured(1); // false
            qDebug() << m.hasCaptured(2); // true
        }
        //! [36]
    }
 
}