Was this page helpful?
Your feedback about this content is important. Let us know what you think.
Additional feedback?
1500 characters remaining
Extension Property

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

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8
Show:
© 2015 Microsoft