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String.IsNullOrEmpty Method

Indicates whether the specified String object is a null reference (Nothing in Visual Basic) or an Empty string.

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

public static bool IsNullOrEmpty (
	string value
)
public static boolean IsNullOrEmpty (
	String value
)
public static function IsNullOrEmpty (
	value : String
) : boolean
Not applicable.

Parameters

value

A String reference.

Return Value

true if the value parameter is a null reference (Nothing in Visual Basic) or an empty string (""); otherwise, false.

IsNullOrEmpty is a convenience method that enables you to simultaneously test whether a String is a null reference (Nothing in Visual Basic) or its value is Empty.

The following code example determines whether each of three strings has a value, is an empty string or is a null reference (Nothing in Visual Basic).

// This example demonstrates the String.IsNullOrEmpty() method
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) == true) 
        return "is null or empty";
    else
        return String.Format("(\"{0}\") is not null or empty", s);
    }
}
/*
This example produces the following results:

String s1 ("abcd") is not null or empty.
String s2 is null or empty.
String s3 is null or empty.

*/

// This example demonstrates the String.IsNullOrEmpty() method
import System.*;

class Sample
{
    public static void main(String[] args)
    {
        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));
    } //main

    public static String Test(String s)
    {
        if (String.IsNullOrEmpty(s) == true) {
            return "is null or empty";
        }
        else {
            return String.Format("(\"{0}\") is not null or empty", s);
        }
    } //Test
} //Sample 
 /*
This example produces the following results:

String s1 ("abcd") is not null or empty.
String s2 is null or empty.
String s3 is null or empty.

*/

Windows 98, Windows Server 2000 SP4, Windows CE, Windows Millennium Edition, Windows Mobile for Pocket PC, Windows Mobile for Smartphone, Windows Server 2003, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP SP2, Windows XP Starter Edition

The Microsoft .NET Framework 3.0 is supported on Windows Vista, Microsoft Windows XP SP2, and Windows Server 2003 SP1.

.NET Framework

Supported in: 3.0, 2.0

.NET Compact Framework

Supported in: 2.0

XNA Framework

Supported in: 1.0

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