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String.IsNullOrEmpty Method

Updated: January 2011

Indicates whether the specified string is Nothing or an Empty string.

Namespace:  System
Assembly:  mscorlib (in mscorlib.dll)
'Declaration
Public Shared Function IsNullOrEmpty ( _
	value As String _
) As Boolean
'Usage
Dim value As String 
Dim returnValue As Boolean 

returnValue = String.IsNullOrEmpty(value)

Parameters

value
Type: System.String

The string to test.

Return Value

Type: System.Boolean
true if the value parameter is Nothing or an empty string (""); otherwise, false.

IsNullOrEmpty is a convenience method that enables you to simultaneously test whether a String is Nothing or its value is String.Empty. It is equivalent to the following code:

result = s Is Nothing OrElse s = String.Empty

The following example determines whether each of three strings has a value, is an empty string or is Nothing.

Class Sample
   Public Shared Sub Main()
      Dim s1 As String = "abcd" 
      Dim s2 As String = "" 
      Dim s3 As String = Nothing

      Console.WriteLine("String s1 {0}.", Test(s1))
      Console.WriteLine("String s2 {0}.", Test(s2))
      Console.WriteLine("String s3 {0}.", Test(s3))
   End Sub 

   Public Shared Function Test(s As String) As String 
      If String.IsNullOrEmpty(s) Then 
         Return "is null or empty" 
      Else 
         Return String.Format("(""{0}"") is not null or empty", s)
      End If 
   End Function  
End Class   
' The example displays the following output: 
'       String s1 ("abcd") is not null or empty. 
'       String s2 is null or empty. 
'       String s3 is null or empty.

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360, Zune

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

.NET Framework

Supported in: 3.5, 3.0, 2.0

.NET Compact Framework

Supported in: 3.5, 2.0

XNA Framework

Supported in: 3.0, 2.0, 1.0

Date

History

Reason

January 2011

Expanded the Remarks section.

Customer feedback.

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