QFileInfo类

╰+哭是因爲堅強的太久メ 2023-07-05 05:29 4阅读 0赞

The [QFileInfo][] class provides system-independent file information. [More...][]

<table> 
 <tbody> 
 <tr> 
 <td>Header:</td> 
 <td>#include &lt;QFileInfo&gt;</td> 
 </tr> 
 <tr> 
 <td>qmake:</td> 
 <td>QT += core</td> 
 </tr> 
 </tbody> 
</table>

*  [List of all members, including inherited members][List of all members_ including inherited members]
 *  [Obsolete members][]

**Note:** All functions in this class are [reentrant][].

## Public Functions ##

<table> 
 <tbody> 
 <tr> 
 <td>&nbsp;</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#QFileInfo-5" rel="nofollow">QFileInfo</a>(const QFileInfo &amp;fileinfo)</td> 
 </tr> 
 <tr> 
 <td>&nbsp;</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#QFileInfo-4" rel="nofollow">QFileInfo</a>(const QDir &amp;dir, const QString &amp;file)</td> 
 </tr> 
 <tr> 
 <td>&nbsp;</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#QFileInfo-3" rel="nofollow">QFileInfo</a>(const QFile &amp;file)</td> 
 </tr> 
 <tr> 
 <td>&nbsp;</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#QFileInfo-2" rel="nofollow">QFileInfo</a>(const QString &amp;file)</td> 
 </tr> 
 <tr> 
 <td>&nbsp;</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#QFileInfo-1" rel="nofollow">QFileInfo</a>()</td> 
 </tr> 
 <tr> 
 <td>QFileInfo &amp;</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#operator-eq-1" rel="nofollow">operator=</a>(QFileInfo &amp;&amp;other)</td> 
 </tr> 
 <tr> 
 <td>QFileInfo &amp;</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#operator-eq" rel="nofollow">operator=</a>(const QFileInfo &amp;fileinfo)</td> 
 </tr> 
 <tr> 
 <td>&nbsp;</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#dtor.QFileInfo" rel="nofollow">~QFileInfo</a>()</td> 
 </tr> 
 <tr> 
 <td>QDir</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#absoluteDir" rel="nofollow">absoluteDir</a>() const</td> 
 </tr> 
 <tr> 
 <td>QString</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#absoluteFilePath" rel="nofollow">absoluteFilePath</a>() const</td> 
 </tr> 
 <tr> 
 <td>QString</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#absolutePath" rel="nofollow">absolutePath</a>() const</td> 
 </tr> 
 <tr> 
 <td>QString</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#baseName" rel="nofollow">baseName</a>() const</td> 
 </tr> 
 <tr> 
 <td>QDateTime</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#birthTime" rel="nofollow">birthTime</a>() const</td> 
 </tr> 
 <tr> 
 <td>QString</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#bundleName" rel="nofollow">bundleName</a>() const</td> 
 </tr> 
 <tr> 
 <td>bool</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#caching" rel="nofollow">caching</a>() const</td> 
 </tr> 
 <tr> 
 <td>QString</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#canonicalFilePath" rel="nofollow">canonicalFilePath</a>() const</td> 
 </tr> 
 <tr> 
 <td>QString</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#canonicalPath" rel="nofollow">canonicalPath</a>() const</td> 
 </tr> 
 <tr> 
 <td>QString</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#completeBaseName" rel="nofollow">completeBaseName</a>() const</td> 
 </tr> 
 <tr> 
 <td>QString</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#completeSuffix" rel="nofollow">completeSuffix</a>() const</td> 
 </tr> 
 <tr> 
 <td>QDir</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#dir" rel="nofollow">dir</a>() const</td> 
 </tr> 
 <tr> 
 <td>bool</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#exists" rel="nofollow">exists</a>() const</td> 
 </tr> 
 <tr> 
 <td>QString</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#fileName" rel="nofollow">fileName</a>() const</td> 
 </tr> 
 <tr> 
 <td>QString</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#filePath" rel="nofollow">filePath</a>() const</td> 
 </tr> 
 <tr> 
 <td>QDateTime</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#fileTime" rel="nofollow">fileTime</a>(QFile::FileTime&nbsp;time) const</td> 
 </tr> 
 <tr> 
 <td>QString</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#group" rel="nofollow">group</a>() const</td> 
 </tr> 
 <tr> 
 <td>uint</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#groupId" rel="nofollow">groupId</a>() const</td> 
 </tr> 
 <tr> 
 <td>bool</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#isAbsolute" rel="nofollow">isAbsolute</a>() const</td> 
 </tr> 
 <tr> 
 <td>bool</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#isBundle" rel="nofollow">isBundle</a>() const</td> 
 </tr> 
 <tr> 
 <td>bool</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#isDir" rel="nofollow">isDir</a>() const</td> 
 </tr> 
 <tr> 
 <td>bool</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#isExecutable" rel="nofollow">isExecutable</a>() const</td> 
 </tr> 
 <tr> 
 <td>bool</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#isFile" rel="nofollow">isFile</a>() const</td> 
 </tr> 
 <tr> 
 <td>bool</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#isHidden" rel="nofollow">isHidden</a>() const</td> 
 </tr> 
 <tr> 
 <td>bool</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#isNativePath" rel="nofollow">isNativePath</a>() const</td> 
 </tr> 
 <tr> 
 <td>bool</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#isReadable" rel="nofollow">isReadable</a>() const</td> 
 </tr> 
 <tr> 
 <td>bool</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#isRelative" rel="nofollow">isRelative</a>() const</td> 
 </tr> 
 <tr> 
 <td>bool</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#isRoot" rel="nofollow">isRoot</a>() const</td> 
 </tr> 
 <tr> 
 <td>bool</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#isSymLink" rel="nofollow">isSymLink</a>() const</td> 
 </tr> 
 <tr> 
 <td>bool</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#isWritable" rel="nofollow">isWritable</a>() const</td> 
 </tr> 
 <tr> 
 <td>QDateTime</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#lastModified" rel="nofollow">lastModified</a>() const</td> 
 </tr> 
 <tr> 
 <td>QDateTime</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#lastRead" rel="nofollow">lastRead</a>() const</td> 
 </tr> 
 <tr> 
 <td>bool</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#makeAbsolute" rel="nofollow">makeAbsolute</a>()</td> 
 </tr> 
 <tr> 
 <td>QDateTime</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#metadataChangeTime" rel="nofollow">metadataChangeTime</a>() const</td> 
 </tr> 
 <tr> 
 <td>QString</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#owner" rel="nofollow">owner</a>() const</td> 
 </tr> 
 <tr> 
 <td>uint</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#ownerId" rel="nofollow">ownerId</a>() const</td> 
 </tr> 
 <tr> 
 <td>QString</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#path" rel="nofollow">path</a>() const</td> 
 </tr> 
 <tr> 
 <td>bool</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#permission" rel="nofollow">permission</a>(QFile::Permissions&nbsp;permissions) const</td> 
 </tr> 
 <tr> 
 <td>QFile::Permissions</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#permissions" rel="nofollow">permissions</a>() const</td> 
 </tr> 
 <tr> 
 <td>void</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#refresh" rel="nofollow">refresh</a>()</td> 
 </tr> 
 <tr> 
 <td>void</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#setCaching" rel="nofollow">setCaching</a>(bool&nbsp;enable)</td> 
 </tr> 
 <tr> 
 <td>void</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#setFile" rel="nofollow">setFile</a>(const QString &amp;file)</td> 
 </tr> 
 <tr> 
 <td>void</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#setFile-1" rel="nofollow">setFile</a>(const QFile &amp;file)</td> 
 </tr> 
 <tr> 
 <td>void</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#setFile-2" rel="nofollow">setFile</a>(const QDir &amp;dir, const QString &amp;file)</td> 
 </tr> 
 <tr> 
 <td>qint64</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#size" rel="nofollow">size</a>() const</td> 
 </tr> 
 <tr> 
 <td>QString</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#suffix" rel="nofollow">suffix</a>() const</td> 
 </tr> 
 <tr> 
 <td>void</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#swap" rel="nofollow">swap</a>(QFileInfo &amp;other)</td> 
 </tr> 
 <tr> 
 <td>QString</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#symLinkTarget" rel="nofollow">symLinkTarget</a>() const</td> 
 </tr> 
 <tr> 
 <td>bool</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#operator-not-eq" rel="nofollow">operator!=</a>(const QFileInfo &amp;fileinfo) const</td> 
 </tr> 
 <tr> 
 <td>bool</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#operator-eq-eq" rel="nofollow">operator==</a>(const QFileInfo &amp;fileinfo) const</td> 
 </tr> 
 </tbody> 
</table>

## Static Public Members ##

<table> 
 <tbody> 
 <tr> 
 <td>bool</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#exists-1" rel="nofollow">exists</a>(const QString &amp;file)</td> 
 </tr> 
 </tbody> 
</table>

## Related Non-Members ##

<table> 
 <tbody> 
 <tr> 
 <td>typedef</td> 
 <td><a href="https://doc.qt.io/archives/qt-5.13/qfileinfo.html#QFileInfoList-typedef" rel="nofollow">QFileInfoList</a></td> 
 </tr> 
 </tbody> 
</table>

## 详细说明 ##

[QFileInfo][]提供有关文件在文件系统中的名称和位置（路径），其访问权限以及它是目录链接还是符号链接等信息。文件的大小和上次修改/读取的时间也可用。[QFileInfo][]也可用于获取有关Qt [资源的信息][Link 1]。

甲[QFileInfo][]可以指向与相对或绝对文件路径的文件。绝对文件路径以目录分隔符“ /”（或Windows上的驱动器规范）开头。相对文件名以目录名或文件名开头，并指定相对于当前工作目录的路径。绝对路径的一个示例是字符串“ / tmp / quartz”。相对路径可能类似于“ src / fatlib”。您可以使用函数[isRelative][]（）来检查[QFileInfo][]是使用相对还是绝对文件路径。您可以调用函数[makeAbsolute][]（）将相对[QFileInfo][]的路径转换为绝对路径。

[QFileInfo处理][QFileInfo]的文件是在构造函数中设置的，或者以后是通过[setFile][]（）设置的。使用[exist][]（）查看文件是否存在，使用[size][]（）获取其大小。

通过[isFile][]（），[isDir][]（）和[isSymLink][]（）获得文件的类型。该[symLinkTarget][]（）函数提供该文件的符号链接指向的名字。

在Unix（包括[macOS][]和iOS）上，此类中的属性getter函数返回目标文件的时间和大小（而非符号链接）之类的属性，因为Unix透明地处理符号链接。使用[QFile][]打开符号链接可以有效地打开链接的目标。例如：

#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

在Windows上，符号链接（快捷方式）是`.lnk`文件。与Unix系统类似，属性获取器返回目标文件的大小，而不是`.lnk`文件本身。请注意，此行为已被弃用，并且可能会在Qt的将来版本中删除，此后该`.lnk`文件将被视为常规文件。

#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

可以使用[path][]（）和[fileName][]（）提取文件名的元素。的[文件名][fileName]（）的部件都可以用被提取[baseName的][baseName]（），[后缀][Link 2]（）或[completeSuffix][]（）。由Qt类创建的目录的[QFileInfo][]对象将没有尾随文件分隔符。如果您希望在自己的文件信息对象中使用尾随分隔符，只需在提供给构造函数或[setFile][]（）的文件名后附加一个。

该文件的日期是由返回（）创建的，[上次更改时间][Link 3]（），[lastRead][]（）和[FILETIME][]（）。有关文件访问权限的信息可通过[isReadable][]（），[isWritable][]（）和[isExecutable][]（）获得。可通过[owner][]（），[ownerId][]（），[group][]（）和[groupId][]（）获得文件的所有权。您可以使用[权限][Link 4]（）函数在单个语句中检查文件的权限和所有权。

**注意：**在NTFS文件系统上，出于性能原因，默认情况下禁用所有权和权限检查。要启用它，请包含以下行：

extern Q_CORE_EXPORT int qt_ntfs_permission_lookup;

然后通过增加和减少`qt_ntfs_permission_lookup`1来打开和关闭权限检查。

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

### 性能问题 ###

[QFileInfo][]的某些功能查询文件系统，但是出于性能原因，某些功能仅对文件名本身起作用。例如：要返回相对文件名的绝对路径，[absolutePath][]（）必须查询文件系统。该[路径][path]（）函数，但是，可以对文件名直接工作，所以它比较快。

**注意：**为了提高性能，[QFileInfo][]缓存有关文件的信息。

因为文件可以被其他用户或程序甚至同一程序的其他部分更改，所以有一个刷新文件信息的函数：[refresh][]（）。如果要关闭[QFileInfo][]的缓存，并在每次您从文件系统请求信息时强制其访问文件系统，请调用[setCaching][]（false）。

**另请参见**[QDir][]和[QFile][]。

## Member Function Documentation ##

### 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* in 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 [QFile][] &*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][QDir_setCurrent](), and [QDir::isRelativePath][QDir_isRelativePath]().

### QFileInfo::QFileInfo() ###

Constructs an empty [QFileInfo][] object.

Note that an empty [QFileInfo][] object contain no file reference.

**See also** [setFile][]().

### 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.

**Warning:** If [filePath][]() is empty the behavior of this function is undefined.

**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.

**Warning:** If [filePath][]() is empty the behavior of this function is undefined.

**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][Link 2](), [completeSuffix][](), and [completeBaseName][]().

### [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][Link 3](), [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"

This function was introduced in Qt 4.3.

**See also** [isBundle][](), [filePath][](), [baseName][](), and [suffix][Link 2]().

### 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][Link 2](), [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][Link 2](), [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`.

**Note:** If the file is a symlink that points to a non-existing file, false is returned.

### `[static]`bool QFileInfo::exists(const [QString][] &*file*) ###

Returns `true` if the *file* exists; otherwise returns `false`.

**Note:** If *file* is a symlink that points to a non-existing file, false is returned.

**Note:** Using this function is faster than using `QFileInfo(file).exists()` for file system access.

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][Link 2]().

### [QString][] QFileInfo::filePath() const ###

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

**See also** [absoluteFilePath][](), [canonicalFilePath][](), and [isRelative][]().

### [QDateTime][] QFileInfo::fileTime([QFile::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][QFile_FileTime] and [QDateTime::isValid][QDateTime_isValid]().

### [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 name is absolute, otherwise returns false if the path is relative.

**See also** [isRelative][]().

### 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).

This function was introduced in Qt 4.3.

**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][Link 4]().

### 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][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).

### 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][Link 1].

**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][QDir_toNativeSeparators](), [QFile::encodeName][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).

**Note:** If the [NTFS permissions][] check has not been enabled, the result on Windows will merely reflect whether the file exists.

**See also** [isWritable][](), [isExecutable][](), and [permission][Link 4]().

### bool QFileInfo::isRelative() const ###

Returns `true` if the file path name is relative, otherwise returns false if 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::isSymLink() 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 and are typically created by the `ln -s` or `mklink` commands, respectively. Opening a symbolic link effectively opens the [link's target][symLinkTarget].

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

Example:

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

**Note:** If the symlink points to a non existing file, [exists][exist]() returns false.

**See also** [isFile][](), [isDir][](), 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).

**Note:** If the [NTFS permissions][] check has not been enabled, the result on Windows will merely reflect whether the file is marked as Read Only.

**See also** [isReadable][](), [isExecutable][](), and [permission][Link 4]().

### [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][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][Link 3]().

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

**See also** [birthTime][](), [lastModified][Link 3](), [metadataChangeTime][](), and [fileTime][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][]().

### [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][Link 3]() 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][QFile_Permissions] *permissions*) const ###

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

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

**Note:** The result might be inaccurate on Windows if the [NTFS permissions][] check has not been enabled.

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][QFile_Permissions] QFileInfo::permissions() const ###

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

**Note:** The result might be inaccurate on Windows if the [NTFS permissions][] check has not been enabled.

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:

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"

**See also** [isFile][](), [isRelative][](), [QDir::setCurrent][QDir_setCurrent](), and [QDir::isRelativePath][QDir_isRelativePath]().

### void QFileInfo::setFile(const [QFile][] &*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][]().

### [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][exist]().

### [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][]().

### 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][exist]() returns `true` if the symlink points to an existing file.

This function was introduced in Qt 4.2.

**See also** [exists][exist](), [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==][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.

**Warning:** This will not compare two different symbolic links pointing to the same file.

**Warning:** Long and short file names that refer to the same file on Windows are treated as if they referred to different files.

**See also** [operator!=][operator 1]().

## Related Non-Members ##

### typedef QFileInfoList ###

Synonym for [QList][]<[QFileInfo][]>.

[QFileInfo]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html
[More...]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#details
[List of all members_ including inherited members]: https://doc.qt.io/archives/qt-5.13/qfileinfo-members.html
[Obsolete members]: https://doc.qt.io/archives/qt-5.13/qfileinfo-obsolete.html
[reentrant]: https://doc.qt.io/archives/qt-5.13/threads-reentrancy.html
[Link 1]: https://doc.qt.io/archives/qt-5.13/resources.html
[isRelative]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#isRelative
[makeAbsolute]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#makeAbsolute
[setFile]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#setFile
[exist]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#exists
[size]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#size
[isFile]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#isFile
[isDir]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#isDir
[isSymLink]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#isSymLink
[symLinkTarget]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#symLinkTarget
[macOS]: https://doc.qt.io/archives/qt-5.13/internationalization.html#macos
[QFile]: https://doc.qt.io/archives/qt-5.13/qfile.html
[path]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#path
[fileName]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#fileName
[baseName]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#baseName
[Link 2]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#suffix
[completeSuffix]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#completeSuffix
[Link 3]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#lastModified
[lastRead]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#lastRead
[FILETIME]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#fileTime
[isReadable]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#isReadable
[isWritable]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#isWritable
[isExecutable]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#isExecutable
[owner]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#owner
[ownerId]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#ownerId
[group]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#group
[groupId]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#groupId
[Link 4]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#permission
[absolutePath]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#absolutePath
[refresh]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#refresh
[setCaching]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#setCaching
[QDir]: https://doc.qt.io/archives/qt-5.13/qdir.html
[QString]: https://doc.qt.io/archives/qt-5.13/qstring.html
[QDir_setCurrent]: https://doc.qt.io/archives/qt-5.13/qdir.html#setCurrent
[QDir_isRelativePath]: https://doc.qt.io/archives/qt-5.13/qdir.html#isRelativePath
[dir]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#dir
[filePath]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#filePath
[canonicalFilePath]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#canonicalFilePath
[canonicalPath]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#canonicalPath
[absoluteFilePath]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#absoluteFilePath
[completeBaseName]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#completeBaseName
[QDateTime]: https://doc.qt.io/archives/qt-5.13/qdatetime.html
[metadataChangeTime]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#metadataChangeTime
[isBundle]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#isBundle
[absoluteDir]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#absoluteDir
[QFile_FileTime]: https://doc.qt.io/archives/qt-5.13/qfiledevice.html#FileTime-enum
[QDateTime_isValid]: https://doc.qt.io/archives/qt-5.13/qdatetime.html#isValid
[uint]: https://doc.qt.io/archives/qt-5.13/qtglobal.html#uint-typedef
[QDir_entryList]: https://doc.qt.io/archives/qt-5.13/qdir.html#entryList
[QDir_toNativeSeparators]: https://doc.qt.io/archives/qt-5.13/qdir.html#toNativeSeparators
[QFile_encodeName]: https://doc.qt.io/archives/qt-5.13/qfile.html#encodeName
[NTFS permissions]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#ntfs-permissions
[isAbsolute]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#isAbsolute
[birthTime]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#birthTime
[QFile_Permissions]: https://doc.qt.io/archives/qt-5.13/qfiledevice.html#Permission-enum
[caching]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#caching
[qint64]: https://doc.qt.io/archives/qt-5.13/qtglobal.html#qint64-typedef
[operator]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#operator-eq-eq
[operator 1]: https://doc.qt.io/archives/qt-5.13/qfileinfo.html#operator-not-eq
[QList]: https://doc.qt.io/archives/qt-5.13/qlist.html