IsNullOrWhiteSpace Method

String.IsNullOrWhiteSpace Method (String)

.NET Framework (current version)
 

Indicates whether a specified string is null, empty, or consists only of white-space characters.

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

Public Shared Function IsNullOrWhiteSpace (
	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 null or String.Empty, or if value consists exclusively of white-space characters.

IsNullOrWhiteSpace is a convenience method that is similar to the following code, except that it offers superior performance:

Return String.IsNullOrEmpty(value) OrElse value.Trim().Length = 0

White-space characters are defined by the Unicode standard. The IsNullOrWhiteSpace method interprets any character that returns a value of true when it is passed to the Char.IsWhiteSpace method as a white-space character.

The following example creates a string array, and then passes each element of the array to the IsNullOrWhiteSpace method.

Module Example
   Public Sub Main()
      Dim values() As String = { Nothing, String.Empty, "ABCDE", 
                                 New String(" "c, 20), "  " + vbTab + "   ", 
                                 New String(ChrW(&h2000), 10) }
      For Each value As String In values
         Console.WriteLine(String.IsNullOrWhiteSpace(value))
      Next
   End Sub
End Module
' The example displays the following output:
'       True
'       True
'       False
'       True
'       True
'       True

Universal Windows Platform
Available since 4.5
.NET Framework
Available since 4.0
Portable Class Library
Supported in: portable .NET platforms
Silverlight
Available since 4.0
Windows Phone Silverlight
Available since 7.1
Windows Phone
Available since 8.1
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