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String.IsNullOrEmpty Method

Updated: January 2011

Indicates whether the specified string is null or an Empty string.

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

public static bool IsNullOrEmpty(
	string value
)

Parameters

value
Type: System.String
The string to test.

Return Value

Type: System.Boolean
true if the value parameter is null or an empty string (""); otherwise, false.

IsNullOrEmpty is a convenience method that enables you to simultaneously test whether a String is null or its value is Empty. It is equivalent to the following code:


result = s == null || s == String.Empty;


The following code example determines whether each of three strings has a value, is an empty string or is null.


using System;

class Example
{
   public static void Demo(System.Windows.Controls.TextBlock outputBlock)
   {
      string s1 = "abcd";
      string s2 = "";
      string s3 = null;

      outputBlock.Text += String.Format("String s1 {0}.", Test(s1)) + "\n";
      outputBlock.Text += String.Format("String s2 {0}.", Test(s2)) + "\n";
      outputBlock.Text += String.Format("String s3 {0}.", Test(s3)) + "\n";
   }

   public static String Test(string s)
   {
      if (String.IsNullOrEmpty(s))
         return "is null or empty";
      else
         return String.Format("(\"{0}\") is not null or empty", s);
   }
}
// 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.


Silverlight

Supported in: 5, 4, 3

Silverlight for Windows Phone

Supported in: Windows Phone OS 7.1, Windows Phone OS 7.0

XNA Framework

Supported in: Xbox 360, Windows Phone OS 7.0

For a list of the operating systems and browsers that are supported by Silverlight, see Supported Operating Systems and Browsers.

Date

History

Reason

January 2011

Expanded the Remarks section.

Customer feedback.

Community Additions

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