QDir Class Reference
^{[QtCore module]}

Detailed Description

The QDir class provides access to directory structures and their contents.

A QDir is used to manipulate path names, access information regarding paths and files, and manipulate the underlying file system. It can also be used to access Qt's resource system.

A QDir can point to a file using either a relative or an absolute path. Absolute paths begin with the directory separator "/" (optionally preceded by a drive specification under Windows). If you always use "/" as a directory separator, Qt will translate your paths to conform to the underlying operating system. Relative file names begin with a directory name or a file name and specify a path relative to the current directory.

An example of an absolute path is the string "/tmp/quartz", a relative path might look like "src/fatlib". You can use the isRelative() or isAbsolute() functions to check if a QDir is using a relative or an absolute file path. Call makeAbsolute() to convert a relative QDir to an absolute one. For a simplified path use cleanPath(). To obtain a path which has no symbolic links or redundant ".." elements use canonicalPath(). The path can be set with setPath(), and changed with cd() and cdUp().

The current() path (and currentPath()), refers to the application's working directory. A QDir's own path is set and retrieved with setPath() and path().

QDir provides several static convenience functions, for example, setCurrent() to set the application's working directory and current() and currentPath() to retrieve the application's working directory. Access to some common paths is provided with the static functions, home(), root(), and temp() which return QDir objects or homePath(), rootPath(), and tempPath() which return the path as a string. For the application's directory, see QApplication::applicationDirPath().

The number of entries in a directory is returned by count(). You can obtain a string list of the names of all the files and directories in a directory with entryList(). If you prefer a list of QFileInfo pointers use entryInfoList(). Both these functions can apply a name filter, an attributes filter (e.g. read-only, files not directories, etc.), and a sort order. The filters and sort may be set with calls to setNameFilters(), setFilter() and setSorting(). They may also be specified in the entryList() and entryInfoList()'s arguments. You can test to see if a filename matches a filter using match().

Create a new directory with mkdir(), rename a directory with rename() and remove an existing directory with rmdir(). Remove a file with remove(). You can query a directory with exists(), isReadable(), isAbsolute(), isRelative(), and isRoot(). You can use refresh() to re-read the directory's data from disk.

To get a path with a filename use filePath(), and to get a directory name use dirName(); neither of these functions checks for the existence of the file or directory. The path() (changeable with setPath()), absolutePath(), absoluteFilePath(), and canonicalPath() are also available.

The list of root directories is provided by drives(); on Unix systems this returns a list containing a single root directory, "/"; on Windows the list will usually contain "C:/", and possibly "D:/", etc.

It is easiest to work with "/" separators in Qt code. If you need to present a path to the user or need a path in a form suitable for a function in the underlying operating system use convertSeparators().

Example (check if a directory exists):

    QDir dir("example");
    if (!dir.exists())
        qWarning("Cannot find the example directory");

(We could also use the static convenience function QFile::exists().)

Example (traversing directories and reading a file):

    QDir dir = QDir::root();                 // "/"
    if (!dir.cd("tmp")) {                    // "/tmp"
        qWarning("Cannot find the \"/tmp\" directory");
    } else {
        QFile file(dir.filePath("ex1.txt")); // "/tmp/ex1.txt"
        if (!file.open(QIODevice::ReadWrite))
            qWarning("Cannot create the file %s", file.name());
    }

A program that lists all the files in the current directory (excluding symbolic links), sorted by size, smallest first:

    #include <QDir>

    #include <stdio.h>

    int main(int argc, char *argv[])
    {
        QDir dir;
        dir.setFilter(QDir::Files | QDir::Hidden | QDir::NoSymLinks);
        dir.setSorting(QDir::Size | QDir::Reversed);

        QFileInfoList list = dir.entryInfoList();
        printf("     Bytes Filename\n");
        for (int i = 0; i < list.size(); ++i) {
            QFileInfo fileInfo = list.at(i);
            printf("%10li %s\n", fileInfo.size(), qPrintable(fileInfo.fileName()));
        }
        return 0;
    }

See also QFileInfo, QFile, and QApplication::applicationDirPath().

Member Type Documentation

enum QDir::Filter
flags QDir::Filters

This enum describes the filtering options available to QDir; e.g. for entryList() and entryInfoList(). The filter value is specified by combining values from the following list using the bitwise OR operator:

Functions that use Filter enum values to filter lists of files and directories will include symbolic links to files and directories unless you set the NoSymLinks value.

If you do not set any of Readable, Writable, or Executable, QDir will set all three of them. This makes the default easy to write, and at the same time useful.

Examples: Readable | Writable means list all files for which the application has read access, write access or both. Dirs | Drives means list drives, directories, all files that the application can read, write or execute, and also symlinks to such files/directories.

The Filters type is a typedef for QFlags<Filter>. It stores an OR combination of Filter values.

typedef QDir::FilterSpec

Use QDir::Filters instead.

enum QDir::SortFlag
flags QDir::SortFlags

This enum describes the sort options available to QDir, e.g. for entryList() and entryInfoList(). The sort value is specified by OR-ing together values from the following list:

You can only specify one of the first four.

If you specify both DirsFirst and Reversed, directories are still put first, but in reverse order; the files will be listed after the directories, again in reverse order.

The SortFlags type is a typedef for QFlags<SortFlag>. It stores an OR combination of SortFlag values.

typedef QDir::SortSpec

Use QDir::SortFlags instead.

Member Function Documentation

QDir::QDir ( const QDir & dir )

Constructs a QDir object that is a copy of the QDir object for directory dir.

See also operator=().

QDir::QDir ( const QString & path = QString() )

Constructs a QDir pointing to the given directory path. If path is empty the program's working directory, ("."), is used.

See also currentPath().

QDir::QDir ( const QString & path, const QString & nameFilter, SortFlags sort = SortFlags( Name | IgnoreCase ), Filters filters = TypeMask )

Constructs a QDir with path path, that filters its entries by name using nameFilter and by attributes using filters. It also sorts the names using sort.

The default nameFilter is an empty string, which excludes nothing; the default filters is TypeMask, which also means exclude nothing. The default sort is Name | IgnoreCase, i.e. sort by name case-insensitively.

If path is an empty string, QDir uses "." (the current directory). If nameFilter is an empty string, QDir uses the name filter "*" (all files).

Note that path need not exist.

See also exists(), setPath(), setNameFilter(), setFilter(), and setSorting().

QDir::~QDir ()

Destroys the QDir object frees up its resources. This has no effect on the underlying directory in the file system.

QString QDir::absoluteFilePath ( const QString & fileName ) const

Returns the absolute path name of a file in the directory. Does not check if the file actually exists in the directory; but see exists(). Redundant multiple separators or "." and ".." directories in fileName are not removed (see cleanPath()).

See also relativeFilePath(), filePath(), and canonicalPath().

QString QDir::absolutePath () const

Returns the absolute path (a path that starts with "/" or with a drive specification), which may contain symbolic links, but never contains redundant ".", ".." or multiple separators.

See also setPath(), canonicalPath(), exists(), cleanPath(), dirName(), and absoluteFilePath().

void QDir::addResourceSearchPath ( const QString & path )   [static]

Adds path to the search paths searched in to find resources that are not specified with an absolute path. The default search path is to search only in the root (:/).

See also The Qt Resource System.

QString QDir::canonicalPath () const

Returns the canonical path, i.e. a path without symbolic links or redundant "." or ".." elements.

On systems that do not have symbolic links this function will always return the same string that absolutePath() returns. If the canonical path does not exist (normally due to dangling symbolic links) canonicalPath() returns an empty string.

Example:

    QString bin = "/local/bin";         // where /local/bin is a symlink to /usr/bin
    QDir binDir(bin);
    QString canonicalBin = binDir.canonicalPath();
    // canonicalBin now equals "/usr/bin"

    QString ls = "/local/bin/ls";       // where ls is the executable "ls"
    QDir lsDir(ls);
    QString canonicalLs = lsDir.canonicalPath();
    // canonicalLS now equals "/usr/bin/ls".

See also path(), absolutePath(), exists(), cleanPath(), dirName(), and absoluteFilePath().

bool QDir::cd ( const QString & dirName )

Changes the QDir's directory to dirName.

Returns true if the new directory exists and is readable; otherwise returns false. Note that the logical cd() operation is not performed if the new directory does not exist.

Calling cd("..") is equivalent to calling cdUp().

See also cdUp(), isReadable(), exists(), and path().

bool QDir::cdUp ()

Changes directory by moving one directory up from the QDir's current directory.

Returns true if the new directory exists and is readable; otherwise returns false. Note that the logical cdUp() operation is not performed if the new directory does not exist.

See also cd(), isReadable(), exists(), and path().

QString QDir::cleanPath ( const QString & path )   [static]

Removes all multiple directory separators "/" and resolves any "."s or ".."s found in the path, path.

Symbolic links are kept. This function does not return the canonical path, but rather the simplest version of the input. For example, "./local" becomes "local", "local/../bin" becomes "bin" and "/local/usr/../bin" becomes "/local/bin".

See also absolutePath() and canonicalPath().

QString QDir::convertSeparators ( const QString & pathName )   [static]

Returns pathName with the '/' separators converted to separators that are appropriate for the underlying operating system.

On Windows, convertSeparators("c:/winnt/system32") returns "c:\winnt\system32".

The returned string may be the same as the argument on some operating systems, for example on Unix.

See also separator().

uint QDir::count () const

Returns the total number of directories and files in the directory.

Equivalent to entryList().count().

See also operator[]() and entryList().

QDir QDir::current ()   [static]

Returns the absolute path of the application's current directory. See currentPath() for details.

See also setCurrent(), drives(), homePath(), rootPath(), and tempPath().

QString QDir::currentPath ()   [static]

Returns the absolute path of the application's current directory.

See also current(), drives(), homePath(), rootPath(), and tempPath().

QString QDir::dirName () const

Returns the name of the directory; this is not the same as the path, e.g. a directory with the name "mail", might have the path "/var/spool/mail". If the directory has no name (e.g. it is the root directory) an empty string is returned.

No check is made to ensure that a directory with this name actually exists; but see exists().

See also path(), filePath(), absolutePath(), and absoluteFilePath().

QFileInfoList QDir::drives ()   [static]

Returns a list of the root directories on this system. On Windows this returns a number of QFileInfo objects containing "C:/", "D:/", etc. On other operating systems, it returns a list containing just one root directory (i.e. "/").

QFileInfoList QDir::entryInfoList ( Filters filters = NoFilter, SortFlags sort = NoSort ) const

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Returns a list of QFileInfo objects for all the files and directories in the directory, ordered in accordance with setSorting() and filtered in accordance with setFilter() and setNameFilters().

The filter and sorting specifications can be overridden using the filters and sort arguments.

Returns an empty list if the directory is unreadable or does not exist or if nothing matches the specification.

See also entryList(), setNameFilters(), setSorting(), setFilter(), isReadable(), and exists().

QFileInfoList QDir::entryInfoList ( const QStringList & nameFilters, Filters filters = NoFilter, SortFlags sort = NoSort ) const

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Returns a list of QFileInfo objects for all the files and directories in the directory, ordered in accordance with setSorting() and filtered in accordance with setFilter() and setNameFilters().

The name filter, file attributes filter, and sorting specifications can be overridden using the nameFilters, filters, and sort arguments.

Returns an empty list if the directory is unreadable or does not exist or if nothing matches the specification.

See also entryList(), setNameFilters(), setSorting(), setFilter(), isReadable(), and exists().

QStringList QDir::entryList ( const QStringList & nameFilters, Filters filters = NoFilter, SortFlags sort = NoSort ) const

Returns a list of the names of all the files and directories in the directory, ordered in accordance with setSorting() and filtered in accordance with setFilter() and setNameFilters().

The name filter, file attributes filter, and the sorting specifications can be overridden using the nameFilters, filters and sort arguments.

Returns an empty list if the directory is unreadable or does not exist or if nothing matches the specification.

See also entryInfoList(), setNameFilters(), setSorting(), and setFilter().

QStringList QDir::entryList ( Filters filters = NoFilter, SortFlags sort = NoSort ) const

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Returns a list of the names of all the files and directories in the directory, ordered in accordance with setSorting() and filtered in accordance with setFilter() and setNameFilters().

The filter and sorting specifications can be overridden using the filters and sort arguments.

Returns an empty list if the directory is unreadable or does not exist or if nothing matches the specification.

See also entryInfoList(), setNameFilters(), setSorting(), and setFilter().

bool QDir::exists ( const QString & name ) const

Returns true if the file called name exists; otherwise returns false.

See also QFileInfo::exists() and QFile::exists().

bool QDir::exists () const

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Returns true if the directory exists; otherwise returns false. (If a file with the same name is found this function will return false).

See also QFileInfo::exists() and QFile::exists().

QString QDir::filePath ( const QString & fileName ) const

Returns the path name of a file in the directory. Does not check if the file actually exists in the directory; but see exists(). If the QDir is relative the returned path name will also be relative. Redundant multiple separators or "." and ".." directories in fileName are not removed (see cleanPath()).

See also dirName(), absoluteFilePath(), isRelative(), and canonicalPath().

Filters QDir::filter () const

Returns the value set by setFilter()

See also setFilter().

QDir QDir::home ()   [static]

Returns the user's home directory. See homePath() for details.

See also drives(), currentPath(), rootPath(), and tempPath().

QString QDir::homePath ()   [static]

Returns the user's home directory.

Under Windows the HOME environment variable is used. If this does not exist the USERPROFILE environment variable is used. If that does not exist the path is formed by concatenating the HOMEDRIVE and HOMEPATH environment variables. If they don't exist the rootPath() is used (this uses the SystemDrive environment variable). If none of these exist "C:" is used.

Under non-Windows operating systems the HOME environment variable is used if it exists, otherwise rootPath() is used.

See also home(), drives(), currentPath(), rootPath(), and tempPath().

bool QDir::isAbsolute () const

Returns true if the directory's path is absolute; otherwise returns false. See isAbsolutePath().

See also isRelative(), makeAbsolute(), and cleanPath().

bool QDir::isAbsolutePath ( const QString & path )   [static]

Returns true if path is absolute; returns false if it is relative.

See also isAbsolute(), isRelativePath(), makeAbsolute(), and cleanPath().

bool QDir::isReadable () const

Returns true if the directory is readable and we can open files by name; otherwise returns false.

Warning: A false value from this function is not a guarantee that files in the directory are not accessible.

See also QFileInfo::isReadable().

bool QDir::isRelative () const

Returns true if the directory path is relative; otherwise returns false. (Under Unix a path is relative if it does not start with a "/").

See also makeAbsolute(), isAbsolute(), isAbsolutePath(), and cleanPath().

bool QDir::isRelativePath ( const QString & path )   [static]

Returns true if path is relative; returns false if it is absolute.

See also isRelative(), isAbsolutePath(), and makeAbsolute().

bool QDir::isRoot () const

Returns true if the directory is the root directory; otherwise returns false.

Note: If the directory is a symbolic link to the root directory this function returns false. If you want to test for this use canonicalPath(), e.g.

    QDir dir("/tmp/root_link");
    dir = dir.canonicalPath();
    if (dir.isRoot())
        qWarning("It is a root link");

See also root() and rootPath().

bool QDir::makeAbsolute ()

Converts the directory path to an absolute path. If it is already absolute nothing happens. Returns true if the conversion succeeded; otherwise returns false.

See also isAbsolute(), isAbsolutePath(), isRelative(), and cleanPath().

bool QDir::match ( const QString & filter, const QString & fileName )   [static]

Returns true if the fileName matches the wildcard (glob) pattern filter; otherwise returns false. The filter may contain multiple patterns separated by spaces or semicolons. The matching is case insensitive.

See also QRegExp wildcard matching, QRegExp::exactMatch(), entryList(), and entryInfoList().

bool QDir::match ( const QStringList & filters, const QString & fileName )   [static]

This is an overloaded member function, provided for convenience. It behaves essentially like the above function.

Returns true if the fileName matches any of the wildcard (glob) patterns in the list of filters; otherwise returns false. The matching is case insensitive.

See also QRegExp wildcard matching, QRegExp::exactMatch(), entryList(), and entryInfoList().

bool QDir::mkdir ( const QString & dirName ) const

Creates a sub-directory called dirName.

Returns true on success; otherwise returns false.

See also rmdir().

bool QDir::mkpath ( const QString & dirPath ) const

Creates the directory path dirPath.

The function will create all parent directories necessary to create the directory.

Returns true if successful; otherwise returns false.

See also rmpath().

QStringList QDir::nameFilters () const

Returns the string list set by setNameFilters()

See also setNameFilters().

QString QDir::path () const

Returns the path. This may contain symbolic links, but never contains redundant ".", ".." or multiple separators.

The returned path can be either absolute or relative (see setPath()).

See also setPath(), absolutePath(), exists(), cleanPath(), dirName(), absoluteFilePath(), convertSeparators(), and makeAbsolute().

void QDir::refresh () const

Refreshes the directory information.

QString QDir::relativeFilePath ( const QString & fileName ) const

Returns the path to fileName relative to the directory.

    QDir dir("/home/bob");
    QString s;

    s = dir.relativePath("images/file.jpg");     // s is "images/file.jpg"
    s = dir.relativePath("/home/mary/file.txt"); // s is "../mary/file.txt"

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

bool QDir::remove ( const QString & fileName )

Removes the file, fileName.

Returns true if the file is removed successfully; otherwise returns false.

bool QDir::rename ( const QString & oldName, const QString & newName )

Renames a file or directory from oldName to newName, and returns true if successful; otherwise returns false.

On most file systems, rename() fails only if oldName does not exist or if newName and oldName are not on the same partition. On Windows, rename() will fail if newName already exists. However, there are also other reasons why rename() can fail. For example, on at least one file system rename() fails if newName points to an open file.

bool QDir::rmdir ( const QString & dirName ) const

Removes the directory specified by dirName.

The directory must be empty for rmdir() to succeed.

Returns true if successful; otherwise returns false.

See also mkdir().

bool QDir::rmpath ( const QString & dirPath ) const

Removes the directory path dirPath.

The function will remove all parent directories in dirPath, provided that they are empty. This is the opposite of mkpath(dirPath).

Returns true if successful; otherwise returns false.

See also mkpath().

QDir QDir::root ()   [static]

Returns the root directory. See rootPath() for details.

See also drives(), current(), home(), and temp().

QString QDir::rootPath ()   [static]

Returns the absolute path for the root directory.

For Unix operating systems this returns "/". For Windows file systems this normally returns "c:/".

See also root(), drives(), currentPath(), homePath(), and tempPath().

QChar QDir::separator ()   [static]

Returns the native directory separator: "/" under Unix (including Mac OS X) and "\" under Windows.

You do not need to use this function to build file paths. If you always use "/", Qt will translate your paths to conform to the underlying operating system. If you want to display paths to the user using their operating system's separator use convertSeparators().

bool QDir::setCurrent ( const QString & path )   [static]

Sets the application's current working directory to path. Returns true if the directory was successfully changed; otherwise returns false.

See also current(), currentPath(), home(), root(), and temp().

void QDir::setFilter ( Filters filters )

Sets the filter used by entryList() and entryInfoList() to filters. The filter is used to specify the kind of files that should be returned by entryList() and entryInfoList(). See QDir::Filter.

See also filter() and setNameFilters().

void QDir::setNameFilters ( const QStringList & nameFilters )

Sets the name filters used by entryList() and entryInfoList() to the list of filters specified by nameFilters.

See also nameFilters() and setFilter().

void QDir::setPath ( const QString & path )

Sets the path of the directory to path. The path is cleaned of redundant ".", ".." and of multiple separators. No check is made to see whether a directory with this path actually exists; but you can check for yourself using exists().

The path can be either absolute or relative. Absolute paths begin with the directory separator "/" (optionally preceded by 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. An example of an absolute path is the string "/tmp/quartz", a relative path might look like "src/fatlib".

See also path(), absolutePath(), exists(), cleanPath(), dirName(), absoluteFilePath(), isRelative(), and makeAbsolute().

void QDir::setSorting ( SortFlags sort )

Sets the sort order used by entryList() and entryInfoList().

The sort is specified by OR-ing values from the enum QDir::SortFlag.

See also sorting() and SortFlag.

SortFlags QDir::sorting () const

Returns the value set by setSorting()

See also setSorting() and SortFlag.

QDir QDir::temp ()   [static]

Returns the system's temporary directory. See tempPath() for details.

See also drives(), currentPath(), homePath(), and rootPath().

QString QDir::tempPath ()   [static]

Returns the system's temporary directory.

On Unix/Linux systems this is usually /tmp; on Windows this is usually the path in the TEMP or TMP environment variable.

See also temp(), drives(), currentPath(), homePath(), and rootPath().

bool QDir::operator!= ( const QDir & dir ) const

Returns true if directory dir and this directory have different paths or different sort or filter settings; otherwise returns false.

Example:

    // The current directory is "/usr/local"
    QDir d1("/usr/local/bin");
    QDir d2("bin");
    if (d1 != d2)
        qDebug("They differ");

QDir & QDir::operator= ( const QDir & dir )

Makes a copy of the dir object and assigns it to this QDir object.

bool QDir::operator== ( const QDir & dir ) const

Returns true if directory dir and this directory have the same path and their sort and filter settings are the same; otherwise returns false.

Example:

    // The current directory is "/usr/local"
    QDir d1("/usr/local/bin");
    QDir d2("bin");
    if (d1 == d2)
        qDebug("They're the same");

QString QDir::operator[] ( int pos ) const

Returns the file name at position pos in the list of file names. Equivalent to entryList().at(index).

Returns an empty string if pos is out of range or if the entryList() function failed.

See also count() and entryList().

Macro Documentation

void Q_INIT_RESOURCE ( name )

Initializes the resources specified by the .qrc file with the base name name. Normally, Qt resources are loaded automatically at startup. The Q_INIT_RESOURCE() macro is necessary on some platforms for resources stored in a static library.

For example, if your application's resources are listed in a file called myapp.qrc, you can ensure that the resources are initialized at startup by adding this line to your main() function:

    Q_INIT_RESOURCE(myapp);

See also The Qt Resource System.