QFileInfo

NAME

SYNOPSIS

#include <qfileinfo.h>

Public Members

DESCRIPTION

QFileInfo provides information about a file's name and position (path) in the file system, its access rights and whether it is a directory or symbolic link, etc. The file's size and last modified/read times are also available.

A QFileInfo can point to a file with either a relative or an absolute file path. Absolute file paths begin with the directory separator "/" (or with a drive specification on Windows). Relative file names begin with a directory name or a file name and specify a path relative to the current working directory. An example of an absolute path is the string "/tmp/quartz". A relative path might look like "src/fatlib". You can use the function isRelative() to check whether a QFileInfo is using a relative or an absolute file path. You can call the function convertToAbs() to convert a relative QFileInfo's path to an absolute path.

The file that the QFileInfo works on is set in the constructor or later with setFile(). Use exists() to see if the file exists and size() to get its size.

To speed up performance, QFileInfo caches information about the file. Because files can be changed by other users or programs, or even by other parts of the same program, there is a function that refreshes the file information: refresh(). If you want to switch off a QFileInfo's caching and force it to access the file system every time you request information from it call setCaching(FALSE).

The file's type is obtained with isFile(), isDir() and isSymLink(). The readLink() function provides the name of the file the symlink points to.

Elements of the file's name can be extracted with dirPath() and fileName(). The fileName()'s parts can be extracted with baseName() and extension().

The file's dates are returned by created(), lastModified() and lastRead(). Information about the file's access permissions is obtained with isReadable(), isWritable() and isExecutable(). The file's ownership is available from owner(), ownerId(), group() and groupId(). You can examine a file's permissions and ownership in a single statement using the permission() function.

If you need to read and traverse directories, see the QDir class.

See also Input/Output and Networking.  

Member Type Documentation

QFileInfo::PermissionSpec

QFileInfo::ReadOwner - The file is readable by the owner of the file.

QFileInfo::WriteOwner - The file is writable by the owner of the file.

QFileInfo::ExeOwner - The file is executable by the owner of the file.

QFileInfo::ReadUser - The file is readable by the user.

QFileInfo::WriteUser - The file is writable by the user.

QFileInfo::ExeUser - The file is executable by the user.

QFileInfo::ReadGroup - The file is readable by the group.

QFileInfo::WriteGroup - The file is writable by the group.

QFileInfo::ExeGroup - The file is executable by the group.

QFileInfo::ReadOther - The file is readable by anyone.

QFileInfo::WriteOther - The file is writable by anyone.

QFileInfo::ExeOther - The file is executable by anyone.

Warning: The semantics of ReadUser, WriteUser and ExeUser are unfortunately not platform independent: on Unix, the rights of the owner of the file are returned and on Windows the rights of the current user are returned. This behavior might change in a future Qt version. If you want to find the rights of the owner of the file, you should use the flags ReadOwner, WriteOwner and ExeOwner. If you want to find out the rights of the current user, you should use isReadable(), isWritable() and isExecutable().  

MEMBER FUNCTION DOCUMENTATION

QFileInfo::QFileInfo ()

QFileInfo::QFileInfo ( const QString & file )

Warning: Some functions might behave in a counter-intuitive way if file has a trailing directory separator.

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

QFileInfo::QFileInfo ( const QFile & file )

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

See also isRelative().  

QFileInfo::QFileInfo ( const QDir & d, const QString & fileName )

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

See also isRelative().  

QFileInfo::QFileInfo ( const QFileInfo & fi )

QFileInfo::~QFileInfo ()

QString QFileInfo::absFilePath () const

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/'.

This function returns the same as filePath(), unless isRelative() is TRUE.

If the QFileInfo is empty it returns QDir::currentDirPath().

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

See also isRelative() and filePath().

Examples:  

QString QFileInfo::baseName ( bool complete = FALSE ) const

If complete is FALSE (the default) the base name consists of all characters in the file name up to (but not including) the first '.' character.

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

The path is not included in either case.

Example:

        QFileInfo fi( "/tmp/archive.tar.gz" );


        QString base = fi.baseName();  // base = "archive"


        base = fi.baseName( TRUE );    // base = "archive.tar"

See also fileName() and extension().  

bool QFileInfo::caching () const

See also setCaching() and refresh().  

bool QFileInfo::convertToAbs ()

If it is already absolute, nothing is done.

See also filePath() and isRelative().  

QDateTime QFileInfo::created () const

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

See also lastModified() and lastRead().  

QDir QFileInfo::dir ( bool absPath = FALSE ) const

If the QFileInfo is relative and absPath is FALSE, the QDir will be relative; otherwise it will be absolute.

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

Example: fileiconview/qfileiconview.cpp.  

QString QFileInfo::dirPath ( bool absPath = FALSE ) const

If absPath is TRUE an absolute path is returned.

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

Example: fileiconview/qfileiconview.cpp.  

bool QFileInfo::exists () const

Examples:  

QString QFileInfo::extension ( bool complete = TRUE ) const

If complete is TRUE (the default), extension() returns the string of all characters in the file name after (but not including) the first '.' character.

If complete is FALSE, extension() returns the string of all characters in the file name after (but not including) the last '.' character.

Example:

        QFileInfo fi( "/tmp/archive.tar.gz" );


        QString ext = fi.extension();  // ext = "tar.gz"


        ext = fi.extension( FALSE );   // ext = "gz"

See also fileName() and baseName().

Example: qdir/qdir.cpp.  

QString QFileInfo::fileName () const

Example:

        QFileInfo fi( "/tmp/archive.tar.gz" );


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

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

Examples:  

QString QFileInfo::filePath () const

See also isRelative() and absFilePath().

Examples:  

QString QFileInfo::group () const

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

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

uint QFileInfo::groupId () const

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

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

bool QFileInfo::isDir () const

See also isFile() and isSymLink().

Examples:  

bool QFileInfo::isExecutable () const

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

bool QFileInfo::isFile () const

See also isDir() and isSymLink().

Examples:  

bool QFileInfo::isHidden () const

On Unix-like operating systems, including Mac OS X, a file is hidden if its name begins with ".". On Windows a file is hidden if its hidden attribute is set.  

bool QFileInfo::isReadable () const

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

Example: distributor/distributor.ui.h.  

bool QFileInfo::isRelative () const

bool QFileInfo::isSymLink () const

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

Examples:  

bool QFileInfo::isWritable () const

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

Example: distributor/distributor.ui.h.  

QDateTime QFileInfo::lastModified () const

See also created() and lastRead().

Example: biff/biff.cpp.  

QDateTime QFileInfo::lastRead () const

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

See also created() and lastModified().

Example: biff/biff.cpp.  

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

QString QFileInfo::owner () const

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

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

uint QFileInfo::ownerId () const

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

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

bool QFileInfo::permission ( int permissionSpec ) const

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

Example:

        QFileInfo fi( "/tmp/archive.tar.gz" );


        if ( fi.permission( QFileInfo::WriteUser | QFileInfo::ReadGroup ) )


            qWarning( "I can change the file; my group can read the file" );


        if ( fi.permission( QFileInfo::WriteGroup | QFileInfo::WriteOther ) )


            qWarning( "The group or others can change the file" );

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

QString QFileInfo::readLink () const

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().  

void QFileInfo::refresh () const

See also setCaching().  

void QFileInfo::setCaching ( bool enable )

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 )

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:

    QString absolute = "/local/bin";


    QString relative = "local/bin";


    QFileInfo absFile( absolute );


    QFileInfo relFile( relative );




    QDir::setCurrent( QDir::rootDirPath() );


    // absFile and relFile now point to the same file




    QDir::setCurrent( "/tmp" );


    // absFile now points to "/local/bin",


    // while relFile points to "/tmp/local/bin"

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

Example: biff/biff.cpp.  

void QFileInfo::setFile ( const QFile & file )

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 & d, const QString & fileName )

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

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

See also isRelative().  

uint QFileInfo::size () const

Example: qdir/qdir.cpp.

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