Path.HasExtension Method (System.IO)

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.NET Framework Class Library

Path.HasExtension Method

Determines whether a path includes a file name extension.

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

Syntax

Visual Basic (Declaration)

Public Shared Function HasExtension ( _
	path As String _
) As Boolean

Visual Basic (Usage)

Dim path As String
Dim returnValue As Boolean

returnValue = Path.HasExtension(path)

public static bool HasExtension (
	string path
)

C++

public:
static bool HasExtension (
	String^ path
)

public static boolean HasExtension (
	String path
)

JScript

public static function HasExtension (
	path : String
) : boolean

Parameters

path: The path to search for an extension.

Return Value

true if the characters that follow the last directory separator (\\ or /) or volume separator (:) in the path include a period (.) followed by one or more characters; otherwise, false.

Exceptions

Exception type	Condition
ArgumentException	path contains one or more of the invalid characters defined in InvalidPathChars, or contains a wildcard character.

Remarks

Starting from the end of path, this method searches for a period (.) followed by at least one character. If this pattern is found before a DirectorySeparatorChar, AltDirectorySeparatorChar, or VolumeSeparatorChar character is encountered, this method returns true.

For an example of using this method, see the Example section below. 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 a file extension.	GetExtension
Retrieve the fully qualified path of a file.	GetFullPath
Retrieve the file name and extension from a path.	GetFileName
Retrieve only the file name from a path.	GetFileNameWithoutExtension
Retrieve only the directory name from a path.	GetDirectoryName
Change the extension of a file.	ChangeExtension
Determine if a directory exists.	Exists
Determine if a file exists.	Exists

Example

The following code example demonstrates the use of the HasExtension method.

Visual Basic

Dim fileName1 As String = "myfile.ext"
Dim fileName2 As String = "mydir\myfile"
Dim pathname As String = "C:\mydir.ext\"
Dim result As Boolean

result = Path.HasExtension(fileName1)
Console.WriteLine("HasExtension('{0}') returns {1}", fileName1, result)

result = Path.HasExtension(fileName2)
Console.WriteLine("HasExtension('{0}') returns {1}", fileName2, result)

result = Path.HasExtension(pathname)
Console.WriteLine("HasExtension('{0}') returns {1}", pathname, result)

' This code produces output similar to the following:
'
' HasExtension('myfile.ext') returns True
' HasExtension('mydir\myfile') returns False
' HasExtension('C:\mydir.ext\') returns False

string fileName1 = "myfile.ext";
string fileName2 = @"mydir\myfile";
string path = @"C:\mydir.ext\";
bool result;

result = Path.HasExtension(fileName1);
Console.WriteLine("HasExtension('{0}') returns {1}", 
    fileName1, result);

result = Path.HasExtension(fileName2);
Console.WriteLine("HasExtension('{0}') returns {1}", 
    fileName2, result);

result = Path.HasExtension(path);
Console.WriteLine("HasExtension('{0}') returns {1}", 
    path, result);

// This code produces output similar to the following:
//
// HasExtension('myfile.ext') returns True
// HasExtension('mydir\myfile') returns False
// HasExtension('C:\mydir.ext\') returns False

C++

String^ fileName1 = "myfile.ext";
String^ fileName2 = "mydir\\myfile";
String^ path = "C:\\mydir.ext\\";
bool result;
result = Path::HasExtension( fileName1 );
Console::WriteLine( "HasExtension('{0}') returns {1}", fileName1, result.ToString() );
result = Path::HasExtension( fileName2 );
Console::WriteLine( "HasExtension('{0}') returns {1}", fileName2, result.ToString() );
result = Path::HasExtension( path );
Console::WriteLine( "HasExtension('{0}') returns {1}", path, result.ToString() );

String fileName1 = "myfile.ext";
String fileName2 = "mydir\\myfile";
String path = "C:\\mydir.ext\\";
boolean result;

result = Path.HasExtension(fileName1);
Console.WriteLine("HasExtension('{0}') returns {1}", 
    fileName1,System.Convert.ToString(result));

result = Path.HasExtension(fileName2);
Console.WriteLine("HasExtension('{0}') returns {1}", 
    fileName2, System.Convert.ToString(result));

result = Path.HasExtension(path);
Console.WriteLine("HasExtension('{0}') returns {1}", 
    path, System.Convert.ToString(result));

JScript

var fileName1 : String = "myfile.ext";
var fileName2 : String  = "mydir\\myfile";
var path : String = "C:\\mydir.ext\\";
var result : boolean;

result = Path.HasExtension(fileName1);
Console.WriteLine("HasExtension('{0}') returns {1}", 
                  fileName1, result);

result = Path.HasExtension(fileName2);
Console.WriteLine("HasExtension('{0}') returns {1}", 
                  fileName2, result);

result = Path.HasExtension(path);
Console.WriteLine("HasExtension('{0}') returns {1}", 
                  path, result);

Platforms

Windows 98, Windows 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

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

Version Information

.NET Framework

Supported in: 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 2.0, 1.0

Reference

Path Class
Path Members
System.IO Namespace

Other Resources

File and Stream I/O
How to: Read Text from a File
How to: Write Text to a File