src_corelib_io_qdirlisting.cpp

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// Copyright (C) 2016 The Qt Company Ltd.
// SPDX-License-Identifier: LicenseRef-Qt-Commercial OR BSD-3-Clause
 
#include <QDirListing>
#include <QFile>
#include <QFileInfo>
 
using namespace Qt::StringLiterals;
 
[[maybe_unused]] static void func() {
    {
        //! [0]
        using ItFlag = QDirListing::IteratorFlag;
        for (const auto &dirEntry : QDirListing(u"/etc"_s, ItFlag::Recursive)) {
            qDebug() << dirEntry.filePath();
            // /etc/.
            // /etc/..
            // /etc/X11
            // /etc/X11/fs
            // ...
        }
        //! [0]
    }
 
    {
        //! [1]
        using F = QDirListing::IteratorFlag;
        QDirListing dirList(u"/sys"_s, QStringList{u"scaling_cur_freq"_s}, F::FilesOnly | F::Recursive);
        for (const auto &dirEntry : dirList) {
            QFile f(dirEntry.filePath());
            if (f.open(QIODevice::ReadOnly))
                qDebug() << f.fileName() << f.readAll().trimmed().toDouble() / 1000 << "MHz";
        }
        //! [1]
    }
 
    {
        //! [2]
        QDirListing audioFileIt(u"/home/johndoe/"_s, QStringList{u"*.mp3"_s, u"*.wav"_s},
                                QDirListing::IteratorFlag::FilesOnly);
        //! [2]
    }
 
    {
        //! [3]
        using ItFlag = QDirListing::IteratorFlag;
        for (const auto &dirEntry : QDirListing(u"/etc"_s, ItFlag::Recursive)) {
            // Faster
            if (dirEntry.fileName().endsWith(u".conf")) { /* ... */ }
 
            // This works, but might be potentially slower, since it has to construct a
            // QFileInfo, whereas (depending on the implementation) the fileName could
            // be known already
            if (dirEntry.fileInfo().fileName().endsWith(u".conf")) { /* ... */ }
        }
        //! [3]
    }
 
    {
        //! [4]
        using ItFlag = QDirListing::IteratorFlag;
        for (const auto &dirEntry : QDirListing(u"/etc"_s, ItFlag::Recursive)) {
            // Both approaches are the same, because DirEntry will have to construct
            // a QFileInfo to get this info (for example, by calling system stat())
 
            if (dirEntry.size() >= 4'000 /* 4KB */) { /* ...*/ }
            if (dirEntry.fileInfo().size() >= 4'000 /* 4KB */) { /* ... */ }
        }
        //! [4]
    }
 
    {
        //! [5]
        using F = QDirListing::IteratorFlag;
        const auto flags = F::FilesOnly | F::Recursive;
        for (const auto &dirEntry : QDirListing(u"/etc"_s, flags)) {
            // ...
        }
        //! [5]
    }
 
    {
        //! [6]
        using F = QDirListing::IteratorFlag;
        const auto flags = F::FilesOnly | F::Recursive | F::ResolveSymlinks;
        for (const auto &dirEntry : QDirListing(u"/etc"_s, flags)) {
            // ...
        }
        //! [6]
    }
 
    {
    //! [7]
        using F = QDirListing::IteratorFlag;
        const auto flags = F::FilesOnly | F::Recursive | F::ResolveSymlinks;
        for (const auto &dirEntry : QDirListing(u"/usr"_s, flags)) {
            // Faster than using name filters, filter ".txt" and ".html" files
            // using QString API
            const QString fileName = dirEntry.fileName();
            if (fileName.endsWith(".txt"_L1) || fileName.endsWith(".html"_L1)) {
                // ...
            }
        }
    }
    //! [7]
}