QFileInfo Class

#ifdef Q_OS_UNIX

QFileInfo info1("/home/bob/bin/untabify");
info1.isSymLink();          // returns true
info1.absoluteFilePath();   // returns "/home/bob/bin/untabify"
info1.size();               // returns 56201
info1.symLinkTarget();      // returns "/opt/pretty++/bin/untabify"

QFileInfo info2(info1.symLinkTarget());
info2.isSymLink();          // returns false
info2.absoluteFilePath();   // returns "/opt/pretty++/bin/untabify"
info2.size();               // returns 56201

#endif

#ifdef Q_OS_WIN

QFileInfo info1("C:\\Users\\Bob\\untabify.lnk");
info1.isSymLink();          // returns true
info1.absoluteFilePath();   // returns "C:/Users/Bob/untabify.lnk"
info1.size();               // returns 63942
info1.symLinkTarget();      // returns "C:/Pretty++/untabify"

QFileInfo info2(info1.symLinkTarget());
info2.isSymLink();          // returns false
info2.absoluteFilePath();   // returns "C:/Pretty++/untabify"
info2.size();               // returns 63942

#endif

extern Q_CORE_EXPORT int qt_ntfs_permission_lookup;

qt_ntfs_permission_lookup++; // turn checking on
qt_ntfs_permission_lookup--; // turn it off again

Member Function Documentation

[since 6.0] QFileInfo::QFileInfo(const QDir &dir, const std::filesystem::path &file)

Constructs a new QFileInfo that gives information about the given file relative to the directory dir.

If dir has a relative path, the QFileInfo will also have a relative path.

If file is an absolute path, then the directory specified by dir will be disregarded.

This function was introduced in Qt 6.0.

[since 6.0] QFileInfo::QFileInfo(const std::filesystem::path &file)

Constructs a new QFileInfo that gives information about the given file.

This function was introduced in Qt 6.0.

See also setFile(), isRelative(), QDir::setCurrent(), and QDir::isRelativePath().

QFileInfo::QFileInfo(const QFileInfo &fileinfo)

Constructs a new QFileInfo that is a copy of the given fileinfo.

QFileInfo::QFileInfo(const QDir &dir, const QString &file)

Constructs a new QFileInfo that gives information about the given file relative to the directory dir.

If dir has a relative path, the QFileInfo will also have a relative path.

If file is an absolute path, then the directory specified by dir will be disregarded.

See also isRelative().

QFileInfo::QFileInfo(const QFileDevice &file)

Constructs a new QFileInfo that gives information about file file.

If the file has a relative path, the QFileInfo will also have a relative path.

See also isRelative().

QFileInfo::QFileInfo(const QString &file)

Constructs a new QFileInfo that gives information about the given file. The file can also include an absolute or relative path.

See also setFile(), isRelative(), QDir::setCurrent(), and QDir::isRelativePath().

QFileInfo::QFileInfo()

Constructs an empty QFileInfo object.

Note that an empty QFileInfo object contain no file reference.

See also setFile().

[since 5.2] QFileInfo &QFileInfo::operator=(QFileInfo &&other)

Move-assigns other to this QFileInfo instance.

This function was introduced in Qt 5.2.

QFileInfo &QFileInfo::operator=(const QFileInfo &fileinfo)

Makes a copy of the given fileinfo and assigns it to this QFileInfo.

QFileInfo::~QFileInfo()

Destroys the QFileInfo and frees its resources.

QDir QFileInfo::absoluteDir() const

Returns the file's absolute path as a QDir object.

See also dir(), filePath(), fileName(), and isRelative().

QString QFileInfo::absoluteFilePath() const

Returns an absolute path including the file name.

The absolute path name consists of the full path and the file name. On Unix this will always begin with the root, '/', directory. On Windows this will always begin 'D:/' where D is a drive letter, except for network shares that are not mapped to a drive letter, in which case the path will begin '//sharename/'. QFileInfo will uppercase drive letters. Note that QDir does not do this. The code snippet below shows this.

    QFileInfo fi("c:/temp/foo"); => fi.absoluteFilePath() => "C:/temp/foo"

This function returns the same as filePath(), unless isRelative() is true. In contrast to canonicalFilePath(), symbolic links or redundant "." or ".." elements are not necessarily removed.

See also filePath(), canonicalFilePath(), and isRelative().

QString QFileInfo::absolutePath() const

Returns a file's path absolute path. This doesn't include the file name.

On Unix the absolute path will always begin with the root, '/', directory. On Windows this will always begin 'D:/' where D is a drive letter, except for network shares that are not mapped to a drive letter, in which case the path will begin '//sharename/'.

In contrast to canonicalPath() symbolic links or redundant "." or ".." elements are not necessarily removed.

See also absoluteFilePath(), path(), canonicalPath(), fileName(), and isRelative().

QString QFileInfo::baseName() const

Returns the base name of the file without the path.

The base name consists of all characters in the file up to (but not including) the first '.' character.

Example:

QFileInfo fi("/tmp/archive.tar.gz");
QString base = fi.baseName();  // base = "archive"

The base name of a file is computed equally on all platforms, independent of file naming conventions (e.g., ".bashrc" on Unix has an empty base name, and the suffix is "bashrc").

See also fileName(), suffix(), completeSuffix(), and completeBaseName().

[since 5.10] QDateTime QFileInfo::birthTime() const

Returns the date and time when the file was created / born.

If the file birth time is not available, this function returns an invalid QDateTime.

If the file is a symlink, the time of the target file is returned (not the symlink).

This function was introduced in Qt 5.10.

See also lastModified(), lastRead(), and metadataChangeTime().

QString QFileInfo::bundleName() const

Returns the name of the bundle.

On macOS and iOS this returns the proper localized name for a bundle if the path isBundle(). On all other platforms an empty QString is returned.

Example:

QFileInfo fi("/Applications/Safari.app");
QString bundle = fi.bundleName();                // name = "Safari"

See also isBundle(), filePath(), baseName(), and suffix().

bool QFileInfo::caching() const

Returns true if caching is enabled; otherwise returns false.

See also setCaching() and refresh().

QString QFileInfo::canonicalFilePath() const

Returns the canonical path including the file name, i.e. an absolute path without symbolic links or redundant "." or ".." elements.

If the file does not exist, canonicalFilePath() returns an empty string.

See also filePath(), absoluteFilePath(), and dir().

QString QFileInfo::canonicalPath() const

Returns the file's path canonical path (excluding the file name), i.e. an absolute path without symbolic links or redundant "." or ".." elements.

If the file does not exist, canonicalPath() returns an empty string.

See also path() and absolutePath().

QString QFileInfo::completeBaseName() const

Returns the complete base name of the file without the path.

The complete base name consists of all characters in the file up to (but not including) the last '.' character.

Example:

QFileInfo fi("/tmp/archive.tar.gz");
QString base = fi.completeBaseName();  // base = "archive.tar"

See also fileName(), suffix(), completeSuffix(), and baseName().

QString QFileInfo::completeSuffix() const

Returns the complete suffix (extension) of the file.

The complete suffix consists of all characters in the file after (but not including) the first '.'.

Example:

QFileInfo fi("/tmp/archive.tar.gz");
QString ext = fi.completeSuffix();  // ext = "tar.gz"

See also fileName(), suffix(), baseName(), and completeBaseName().

QDir QFileInfo::dir() const

Returns the path of the object's parent directory as a QDir object.

Note: The QDir returned always corresponds to the object's parent directory, even if the QFileInfo represents a directory.

For each of the following, dir() returns the QDir "~/examples/191697".

    QFileInfo fileInfo1("~/examples/191697/.");
    QFileInfo fileInfo2("~/examples/191697/..");
    QFileInfo fileInfo3("~/examples/191697/main.cpp");

For each of the following, dir() returns the QDir ".".

    QFileInfo fileInfo4(".");
    QFileInfo fileInfo5("..");
    QFileInfo fileInfo6("main.cpp");

See also absolutePath(), filePath(), fileName(), isRelative(), and absoluteDir().

bool QFileInfo::exists() const

Returns true if the file exists; otherwise returns false.

[static, since 5.2] bool QFileInfo::exists(const QString &file)

Returns true if the file exists; otherwise returns false.

This function was introduced in Qt 5.2.

QString QFileInfo::fileName() const

Returns the name of the file, excluding the path.

Example:

QFileInfo fi("/tmp/archive.tar.gz");
QString name = fi.fileName();                // name = "archive.tar.gz"

Note that, if this QFileInfo object is given a path ending in a slash, the name of the file is considered empty.

See also isRelative(), filePath(), baseName(), and suffix().

QString QFileInfo::filePath() const

Returns the file name, including the path (which may be absolute or relative).

See also absoluteFilePath(), canonicalFilePath(), and isRelative().

[since 5.10] QDateTime QFileInfo::fileTime(QFile::FileTime time) const

Returns the file time specified by time. If the time cannot be determined, an invalid date time is returned.

If the file is a symlink, the time of the target file is returned (not the symlink).

This function was introduced in Qt 5.10.

See also QFile::FileTime and QDateTime::isValid().

[since 6.0] std::filesystem::path QFileInfo::filesystemAbsoluteFilePath() const

Returns absoluteFilePath() as a std::filesystem::path.

This function was introduced in Qt 6.0.

See also absoluteFilePath().

[since 6.0] std::filesystem::path QFileInfo::filesystemAbsolutePath() const

Returns absolutePath() as a std::filesystem::path.

This function was introduced in Qt 6.0.

See also absolutePath().

[since 6.0] std::filesystem::path QFileInfo::filesystemCanonicalFilePath() const

Returns canonicalFilePath() as a std::filesystem::path.

This function was introduced in Qt 6.0.

See also canonicalFilePath().

[since 6.0] std::filesystem::path QFileInfo::filesystemCanonicalPath() const

Returns canonicalPath() as a std::filesystem::path.

This function was introduced in Qt 6.0.

See also canonicalPath().

[since 6.0] std::filesystem::path QFileInfo::filesystemFilePath() const

Returns filePath() as a std::filesystem::path.

This function was introduced in Qt 6.0.

See also filePath().

[since 6.2] std::filesystem::path QFileInfo::filesystemJunctionTarget() const

Returns junctionTarget() as a std::filesystem::path.

This function was introduced in Qt 6.2.

See also junctionTarget().

[since 6.0] std::filesystem::path QFileInfo::filesystemPath() const

Returns path() as a std::filesystem::path.

This function was introduced in Qt 6.0.

See also path().

[since 6.0] std::filesystem::path QFileInfo::filesystemSymLinkTarget() const

Returns symLinkTarget() as a std::filesystem::path.

This function was introduced in Qt 6.0.

See also symLinkTarget().

QString QFileInfo::group() const

Returns the group of the file. On Windows, on systems where files do not have groups, or if an error occurs, an empty string is returned.

This function can be time consuming under Unix (in the order of milliseconds).

If the file is a symlink, this function returns the owning group of the target (not the symlink).

See also groupId(), owner(), and ownerId().

uint QFileInfo::groupId() const

Returns the id of the group the file belongs to.

On Windows and on systems where files do not have groups this function always returns (uint) -2.

If the file is a symlink, this function returns the id of the group owning the target (not the symlink).

See also group(), owner(), and ownerId().

bool QFileInfo::isAbsolute() const

Returns true if the file path is absolute, otherwise returns false (i.e. the path is relative).

See also isRelative().

[since 6.4] bool QFileInfo::isAlias() const

Returns true if this object points to an alias; otherwise returns false.

Aliases only exist on macOS. They are treated as regular files, so opening an alias will open the file itself. In order to open the file or directory an alias references use symLinkTarget().

This function was introduced in Qt 6.4.

See also isFile(), isDir(), isSymLink(), and symLinkTarget().

bool QFileInfo::isBundle() const

Returns true if this object points to a bundle or to a symbolic link to a bundle on macOS and iOS; otherwise returns false.

If the file is a symlink, this function returns true if the target is a bundle (not the symlink).

See also isDir(), isSymLink(), and isFile().

bool QFileInfo::isDir() const

Returns true if this object points to a directory or to a symbolic link to a directory; otherwise returns false.

If the file is a symlink, this function returns true if the target is a directory (not the symlink).

See also isFile(), isSymLink(), and isBundle().

bool QFileInfo::isExecutable() const

Returns true if the file is executable; otherwise returns false.

If the file is a symlink, this function returns true if the target is executable (not the symlink).

See also isReadable(), isWritable(), and permission().

bool QFileInfo::isFile() const

Returns true if this object points to a file or to a symbolic link to a file. Returns false if the object points to something which isn't a file, such as a directory.

If the file is a symlink, this function returns true if the target is a regular file (not the symlink).

See also isDir(), isSymLink(), and isBundle().

bool QFileInfo::isHidden() const

Returns true if this is a `hidden' file; otherwise returns false.

Note: This function returns true for the special entries "." and ".." on Unix, even though QDir::entryList threats them as shown. And note that, since this function inspects the file name, on Unix it will inspect the name of the symlink, if this file is a symlink, not the target's name.

On Windows, this function returns true if the target file is hidden (not the symlink).

[since 5.15] bool QFileInfo::isJunction() const

Returns true if the object points to a junction; otherwise returns false.

Junctions only exist on Windows' NTFS file system, and are typically created by the mklink command. They can be thought of as symlinks for directories, and can only be created for absolute paths on the local volume.

This function was introduced in Qt 5.15.

[since 5.0] bool QFileInfo::isNativePath() const

Returns true if the file path can be used directly with native APIs. Returns false if the file is otherwise supported by a virtual file system inside Qt, such as the Qt Resource System.

Note: Native paths may still require conversion of path separators and character encoding, depending on platform and input requirements of the native API.

This function was introduced in Qt 5.0.

See also QDir::toNativeSeparators(), QFile::encodeName(), filePath(), absoluteFilePath(), and canonicalFilePath().

bool QFileInfo::isReadable() const

Returns true if the user can read the file; otherwise returns false.

If the file is a symlink, this function returns true if the target is readable (not the symlink).

See also isWritable(), isExecutable(), and permission().

bool QFileInfo::isRelative() const

Returns true if the file path is relative, otherwise returns false (i.e. the path is absolute). (E.g. under Unix a path is absolute if it begins with a "/").

See also isAbsolute().

bool QFileInfo::isRoot() const

Returns true if the object points to a directory or to a symbolic link to a directory, and that directory is the root directory; otherwise returns false.

bool QFileInfo::isShortcut() const

Returns true if this object points to a shortcut; otherwise returns false.

Shortcuts only exist on Windows and are typically .lnk files. For instance, true will be returned for shortcuts (*.lnk files) on Windows, but false will be returned on Unix (including macOS and iOS).

The shortcut (.lnk) files are treated as regular files. Opening those will open the .lnk file itself. In order to open the file a shortcut references to, it must uses symLinkTarget() on a shortcut.

See also isFile(), isDir(), isSymbolicLink(), and symLinkTarget().

bool QFileInfo::isSymLink() const

Returns true if this object points to a symbolic link, shortcut, or alias; otherwise returns false.

Symbolic links exist on Unix (including macOS and iOS) and Windows and are typically created by the ln -s or mklink commands, respectively. Opening a symbolic link effectively opens the link's target.

In addition, true will be returned for shortcuts (*.lnk files) on Windows, and aliases on macOS. This behavior is deprecated and will likely change in a future version of Qt. Opening a shortcut or alias will open the .lnk or alias file itself.

Example:

QFileInfo info(fileName);
if (info.isSymLink())
    fileName = info.symLinkTarget();

See also isFile(), isDir(), and symLinkTarget().

bool QFileInfo::isSymbolicLink() const

Returns true if this object points to a symbolic link; otherwise returns false.

Symbolic links exist on Unix (including macOS and iOS) and Windows (NTFS-symlink) and are typically created by the ln -s or mklink commands, respectively.

Unix handles symlinks transparently. Opening a symbolic link effectively opens the link's target.

In contrast to isSymLink(), false will be returned for shortcuts (*.lnk files) on Windows and aliases on macOS. Use QFileInfo::isShortcut() and QFileInfo::isAlias() instead.

See also isFile(), isDir(), isShortcut(), and symLinkTarget().

bool QFileInfo::isWritable() const

Returns true if the user can write to the file; otherwise returns false.

If the file is a symlink, this function returns true if the target is writeable (not the symlink).

See also isReadable(), isExecutable(), and permission().

[since 6.2] QString QFileInfo::junctionTarget() const

Resolves an NTFS junction to the path it references.

Returns the absolute path to the directory an NTFS junction points to, or an empty string if the object is not an NTFS junction.

There is no guarantee that the directory named by the NTFS junction actually exists.

This function was introduced in Qt 6.2.

See also isJunction(), isFile(), isDir(), isSymLink(), isSymbolicLink(), and isShortcut().

QDateTime QFileInfo::lastModified() const

Returns the date and local time when the file was last modified.

If the file is a symlink, the time of the target file is returned (not the symlink).

See also birthTime(), lastRead(), metadataChangeTime(), and fileTime().

QDateTime QFileInfo::lastRead() const

Returns the date and local time when the file was last read (accessed).

On platforms where this information is not available, returns the same as lastModified().

If the file is a symlink, the time of the target file is returned (not the symlink).

See also birthTime(), lastModified(), metadataChangeTime(), and fileTime().

bool QFileInfo::makeAbsolute()

Converts the file's path to an absolute path if it is not already in that form. Returns true to indicate that the path was converted; otherwise returns false to indicate that the path was already absolute.

See also filePath() and isRelative().

[since 5.10] QDateTime QFileInfo::metadataChangeTime() const

Returns the date and time when the file metadata was changed. A metadata change occurs when the file is created, but it also occurs whenever the user writes or sets inode information (for example, changing the file permissions).

If the file is a symlink, the time of the target file is returned (not the symlink).

This function was introduced in Qt 5.10.

See also lastModified() and lastRead().

QString QFileInfo::owner() const

Returns the owner of the file. On systems where files do not have owners, or if an error occurs, an empty string is returned.

This function can be time consuming under Unix (in the order of milliseconds). On Windows, it will return an empty string unless the NTFS permissions check has been enabled.

If the file is a symlink, this function returns the owner of the target (not the symlink).

See also ownerId(), group(), and groupId().

uint QFileInfo::ownerId() const

Returns the id of the owner of the file.

On Windows and on systems where files do not have owners this function returns ((uint) -2).

If the file is a symlink, this function returns the id of the owner of the target (not the symlink).

See also owner(), group(), and groupId().

QString QFileInfo::path() const

Returns the file's path. This doesn't include the file name.

Note that, if this QFileInfo object is given a path ending in a slash, the name of the file is considered empty and this function will return the entire path.

See also filePath(), absolutePath(), canonicalPath(), dir(), fileName(), and isRelative().

bool QFileInfo::permission(QFile::Permissions permissions) const

Tests for file permissions. The permissions argument can be several flags of type QFile::Permissions OR-ed together to check for permission combinations.

On systems where files do not have permissions this function always returns true.

Example:

QFileInfo fi("/tmp/archive.tar.gz");
if (fi.permission(QFile::WriteUser | QFile::ReadGroup))
    qWarning("I can change the file; my group can read the file");
if (fi.permission(QFile::WriteGroup | QFile::WriteOther))
    qWarning("The group or others can change the file");

If the file is a symlink, this function checks the permissions of the target (not the symlink).

See also isReadable(), isWritable(), and isExecutable().

QFile::Permissions QFileInfo::permissions() const

Returns the complete OR-ed together combination of QFile::Permissions for the file.

If the file is a symlink, this function returns the permissions of the target (not the symlink).

void QFileInfo::refresh()

Refreshes the information about the file, i.e. reads in information from the file system the next time a cached property is fetched.

void QFileInfo::setCaching(bool enable)

If enable is true, enables caching of file information. If enable is false caching is disabled.

When caching is enabled, QFileInfo reads the file information from the file system the first time it's needed, but generally not later.

Caching is enabled by default.

See also refresh() and caching().

void QFileInfo::setFile(const QString &file)

Sets the file that the QFileInfo provides information about to file.

The file can also include an absolute or relative file path. Absolute paths begin with the directory separator (e.g. "/" under Unix) or a drive specification (under Windows). Relative file names begin with a directory name or a file name and specify a path relative to the current directory.

Example:

QFileInfo info("/usr/bin/env");

QString path = info.absolutePath(); // path = /usr/bin
QString base = info.baseName(); // base = env

info.setFile("/etc/hosts");

path = info.absolutePath(); // path = /etc
base = info.baseName(); // base = hosts

See also isFile(), isRelative(), QDir::setCurrent(), and QDir::isRelativePath().

void QFileInfo::setFile(const QFileDevice &file)

This is an overloaded function.

Sets the file that the QFileInfo provides information about to file.

If file includes a relative path, the QFileInfo will also have a relative path.

See also isRelative().

void QFileInfo::setFile(const QDir &dir, const QString &file)

This is an overloaded function.

Sets the file that the QFileInfo provides information about to file in directory dir.

If file includes a relative path, the QFileInfo will also have a relative path.

See also isRelative().

[since 6.0] void QFileInfo::setFile(const std::filesystem::path &file)

Sets the file that the QFileInfo provides information about to file.

This function was introduced in Qt 6.0.

qint64 QFileInfo::size() const

Returns the file size in bytes. If the file does not exist or cannot be fetched, 0 is returned.

If the file is a symlink, the size of the target file is returned (not the symlink).

See also exists().

[since 6.0] void QFileInfo::stat()

Reads all attributes from the file system.

This is useful when information about the file system is collected in a worker thread, and then passed to the UI in the form of caching QFileInfo instances.

This function was introduced in Qt 6.0.

See also setCaching() and refresh().

QString QFileInfo::suffix() const

Returns the suffix (extension) of the file.

The suffix consists of all characters in the file after (but not including) the last '.'.

Example:

QFileInfo fi("/tmp/archive.tar.gz");
QString ext = fi.suffix();  // ext = "gz"

The suffix of a file is computed equally on all platforms, independent of file naming conventions (e.g., ".bashrc" on Unix has an empty base name, and the suffix is "bashrc").

See also fileName(), completeSuffix(), baseName(), and completeBaseName().

[since 5.0] void QFileInfo::swap(QFileInfo &other)

Swaps this file info with other. This function is very fast and never fails.

This function was introduced in Qt 5.0.

QString QFileInfo::symLinkTarget() const

Returns the absolute path to the file or directory a symbolic link points to, or an empty string if the object isn't a symbolic link.

This name may not represent an existing file; it is only a string. QFileInfo::exists() returns true if the symlink points to an existing file.

See also exists(), isSymLink(), isDir(), and isFile().

bool QFileInfo::operator!=(const QFileInfo &fileinfo) const

Returns true if this QFileInfo object refers to a different file than the one specified by fileinfo; otherwise returns false.

See also operator==().

bool QFileInfo::operator==(const QFileInfo &fileinfo) const

Returns true if this QFileInfo object refers to a file in the same location as fileinfo; otherwise returns false.

Note that the result of comparing two empty QFileInfo objects, containing no file references (file paths that do not exist or are empty), is undefined.

See also operator!=().

QDirIterator it(dir);
while (it.hasNext()) {
    // Implicit conversion from QString (returned by it.next()):
    // may create unnecessary data structures and cause additional
    // accesses to the file system. Unless this macro is defined,
    // this line does not compile.

    QFileInfo fi = it.next();

    ~~~
}

QDirIterator it(dir);
while (it.hasNext()) {
    // Extract the QFileInfo from the iterator directly:
    QFileInfo fi = it.nextFileInfo();

    ~~~
}

QFileInfo fi1 = some_string; // Does not compile unless this macro is defined
QFileInfo fi2(some_string);  // OK
QFileInfo fi3{some_string};  // Possibly better, avoids the risk of the Most Vexing Parse
auto fi4 = QFileInfo(some_string); // OK