FileSystemInfo.Extension Property

Gets the string representing the extension part of the file.

Namespace:  System.IO
Assembly:  mscorlib (in mscorlib.dll)

public string Extension { get; }

Property Value

Type: System.String
A string containing the FileSystemInfo extension.

The Extension property returns the FileSystemInfo extension, including the period (.). For example, for a file c:\NewFile.txt, this property returns ".txt".

The following table lists examples of other typical or related I/O tasks.

To do this...

See the example in this topic...

Create a text file.

How to: Write Text to a File

Write to a text file.

How to: Write Text to a File

Read from a text file.

How to: Read Text from a File

Retrieve the fully qualified path of a file.

GetFullPath

Retrieve only the file name a path.

GetFileNameWithoutExtension

Retrieve only the directory name from a path.

GetDirectoryName

Change the extension of a file.

ChangeExtension

.NET Framework

Supported in: 4.6, 4.5, 4, 3.5, 3.0, 2.0, 1.1, 1.0

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

The .NET Framework does not support all versions of every platform. For a list of the supported versions, see .NET Framework System Requirements.

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