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String.IsNullOrWhiteSpace Method

.NET Framework 4

Other Versions

Indicates whether a specified string is Nothing, empty, or consists only of white-space characters.

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

Syntax

C++

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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 Nothing or String.Empty, or if value consists exclusively of white-space characters.

Remarks

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

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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.

Examples

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

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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

Version Information

.NET Framework

Supported in: 4

.NET Framework Client Profile

Supported in: 4

Platforms

Windows 7, Windows Vista SP1 or later, Windows XP SP3, Windows Server 2008 (Server Core not supported), Windows Server 2008 R2 (Server Core supported with SP1 or later), Windows Server 2003 SP2

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

Reference

String Class

System Namespace

IsNullOrEmpty

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FAQ

VB Programmers: Null means Nothing in this method name

This method favours C# in its name - Null means Nothing!

The method will test if the input string is Nothing (null in C#) before trying to see if it contains only whitespace.

This highlights the following possible naming confusion:

VB: Nothing

empty reference for object types or default value when used in an assignment for simple types

C#: null

empty reference for object types or default value when used in an assignment for simple types

VB and C#: System.DBNull

the .NET equivalent of the SQL NULL

In light of this it seems a bit leading to use a language specific keyword like "null" in the name of a core function.

The same criticism applies to IsNullOrEmpty.

History

6/16/2011
James Close