String.IsNullOrEmpty Method

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;

You can use the IsNullOrWhiteSpace method to test whether a string is null, 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 null.

using System;

class Sample 
{
    public static void Main() 
    {
    string s1 = "abcd";
    string s2 = "";
    string s3 = null;

    Console.WriteLine("String s1 {0}.", Test(s1));
    Console.WriteLine("String s2 {0}.", Test(s2));
    Console.WriteLine("String s3 {0}.", Test(s3));
    }

    public static String Test(string s)
    {
    if (String.IsNullOrEmpty(s)) 
        return "is null or empty";
    else 
        return String.Format("(\"{0}\") is neither null nor empty", s);
    }
}
// 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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