String.IsNullOrEmpty Method (System)

IsNullOrEmpty Method

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Microsoft Visual Studio 2008/.NET Framework 3.5

Other versions are also available for the following:

.NET Framework Class Library

String..::.IsNullOrEmpty Method

Updated: November 2007

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

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

Syntax

Visual Basic (Declaration)

Public Shared Function IsNullOrEmpty ( _
    value As String _
) As Boolean

Visual Basic (Usage)

Dim value As String
Dim returnValue As Boolean

returnValue = String.IsNullOrEmpty(value)

public static bool IsNullOrEmpty(
    string value
)

Visual C++

public:
static bool IsNullOrEmpty(
    String^ value
)

public static boolean IsNullOrEmpty(
    String value
)

JScript

public static function IsNullOrEmpty(
    value : String
) : boolean

Parameters

value: Type: System..::.String
A String reference.

Return Value

Type: System..::.Boolean

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

Remarks

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

Examples

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

Visual Basic

' This example demonstrates the String.IsNullOrEmpty() method
Imports System

Class Sample
   Public Shared Sub Main()
      Dim s1 As String = "abcd"
      Dim s2 As String = ""
      Dim s3 As String = Nothing

      Console.WriteLine("String s1 {0}.", Test(s1))
      Console.WriteLine("String s2 {0}.", Test(s2))
      Console.WriteLine("String s3 {0}.", Test(s3))
   End Sub 'Main

   Public Shared Function Test(s As String) As [String]
      If [String].IsNullOrEmpty(s) = True Then
         Return "is null or empty"
      Else
         Return String.Format("(""{0}"") is not null or empty", s)
      End If
   End Function 'Test
End Class '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.
'

// 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.

*/

Visual C++

// This example demonstrates the String.IsNullOrEmpty() method
using namespace System;
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 );
}

int main()
{
   String^ s1 = "abcd";
   String^ s2 = "";
   String^ s3 = nullptr;
   Console::WriteLine( "String s1 {0}.", Test( s1 ) );
   Console::WriteLine( "String s2 {0}.", Test( s2 ) );
   Console::WriteLine( "String s3 {0}.", Test( s3 ) );
}

/*
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.

*/

Platforms

Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2003, Windows Server 2000 SP4, Windows Millennium Edition, Windows 98, Windows CE, Windows Mobile for Smartphone, Windows Mobile for Pocket PC, Xbox 360

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

Version Information