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String.IsNullOrEmpty Method

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

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 Empty. It is equivalent to the following code:

result = s Is Nothing OrElse s = String.Empty

You can use the IsNullOrWhiteSpace method to test whether a string is Nothing, its value is String.Empty, or it consists only of white-space characters.

The following example examines three strings and determines whether each string 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 neither null nor empty", s)
      End If 
   End Function  
End Class   
' The example displays the following output: 
'       String s1 ("abcd") is neither null nor empty. 
'       String s2 is null or empty. 
'       String s3 is null or empty.

.NET Framework

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

.NET Framework Client Profile

Supported in: 4, 3.5 SP1

XNA Framework

Supported in: 3.0, 2.0, 1.0

Portable Class Library

Supported in: Portable Class Library

Supported in: Windows Phone 8.1

Supported in: Windows Phone Silverlight 8.1

Supported in: Windows Phone Silverlight 8
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