QFileInfo Class Reference
[QtCore module]

Detailed Description

The QFileInfo class provides system-independent file information.

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. QFileInfo can also be used to obtain information about a Qt resource.

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 makeAbsolute() 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.

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

On Unix (including Mac OS X), the symlink has the same size() has the file it points to, because Unix handles symlinks transparently; similarly, opening a symlink using QFile effectively opens the link's target. For example:

 #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

On Windows, symlinks (shortcuts) are .lnk files. The reported size() is that of the symlink (not the link's target), and opening a symlink using QFile opens the .lnk file. For example:

 #ifdef Q_OS_WIN

 QFileInfo info1("C:\\Documents and Settings\\Bob\\untabify.lnk");
 info1.isSymLink();          // returns true
 info1.absoluteFilePath();   // returns "C:/Documents and Settings/Bob/untabify.lnk"
 info1.size();               // returns 743
 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

Elements of the file's name can be extracted with path() and fileName(). The fileName()'s parts can be extracted with baseName(), suffix() or completeSuffix(). QFileInfo objects to directories created by Qt classes will not have a trailing file separator. If you wish to use trailing separators in your own file info objects, just append one to the file name given to the constructors or setFile().

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.

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

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

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

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

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

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

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

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

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

 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");

 QString absolute = "/local/bin";
 QString relative = "local/bin";
 QFileInfo absFile(absolute);
 QFileInfo relFile(relative);

 QDir::setCurrent(QDir::rootPath());
 // 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"

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