String.IsNullOrWhiteSpace Method

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

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

public static bool IsNullOrWhiteSpace(
	string value
)

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) || 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.

using System;

public class Example
{
   public static void Main()
   {
      string[] values = { null, String.Empty, "ABCDE", 
                          new String(' ', 20), "  \t   ", 
                          new String('\u2000', 10) };
      foreach (string value in values)
         Console.WriteLine(String.IsNullOrWhiteSpace(value));
   }
}
// The example displays the following output: 
//       True 
//       True 
//       False 
//       True 
//       True 
//       True

.NET Framework

Supported in: 4.5, 4

.NET Framework Client Profile

Supported in: 4

Portable Class Library

Supported in: Portable Class Library

.NET for Windows Store apps

Supported in: Windows 8

.NET for Windows Phone apps

Supported in: Windows Phone 8.1, Windows Phone Silverlight 8.1, Windows Phone Silverlight 8

Windows Phone 8.1, Windows Phone 8, Windows 8.1, Windows Server 2012 R2, Windows 8, Windows Server 2012, Windows 7, Windows Vista SP2, Windows Server 2008 (Server Core Role not supported), Windows Server 2008 R2 (Server Core Role supported with SP1 or later; Itanium not supported)

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

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