Object.ReferenceEquals Method (System)

ReferenceEquals Method

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This page is specific to

Microsoft Visual Studio 2008/.NET Framework 3.5

Other versions are also available for the following:

.NET Framework Class Library

Object..::.ReferenceEquals Method

Determines whether the specified Object instances are the same instance.

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

Syntax

Visual Basic (Declaration)

Public Shared Function ReferenceEquals ( _
    objA As Object, _
    objB As Object _
) As Boolean

Visual Basic (Usage)

Dim objA As Object
Dim objB As Object
Dim returnValue As Boolean

returnValue = Object.ReferenceEquals(objA, _
    objB)

public static bool ReferenceEquals(
    Object objA,
    Object objB
)

Visual C++

public:
static bool ReferenceEquals(
    Object^ objA, 
    Object^ objB
)

JScript

public static function ReferenceEquals(
    objA : Object, 
    objB : Object
) : boolean

Parameters

objA: Type: System..::.Object
The first Object to compare.

objB: Type: System..::.Object
The second Object to compare.

Return Value

Type: System..::.Boolean
true if objA is the same instance as objB or if both are null references; otherwise, false.

Examples

The following code example uses ReferenceEquals to determine if two objects are the same instance.

Visual Basic

Imports System

Public Class App
    Public Shared Sub Main() 
        Dim o As Object = Nothing
        Dim p As Object = Nothing
        Dim q As New Object
        Console.WriteLine(Object.ReferenceEquals(o, p))
        p = q
        Console.WriteLine(Object.ReferenceEquals(p, q))
        Console.WriteLine(Object.ReferenceEquals(o, p))
    End Sub 
End Class 
' This code produces the following output:
'
' True
' True
' False
'

using System;

class MyClass {

   static void Main() {
      object o = null;
      object p = null;
      object q = new Object();

      Console.WriteLine(Object.ReferenceEquals(o, p));
      p = q;
      Console.WriteLine(Object.ReferenceEquals(p, q));
      Console.WriteLine(Object.ReferenceEquals(o, p));
   }
}


/*

This code produces the following output.

True
True
False

*/

Visual C++

using namespace System;
int main()
{
   Object^ o = nullptr;
   Object^ p = nullptr;
   Object^ q = gcnew Object;
   Console::WriteLine( Object::ReferenceEquals( o, p ) );
   p = q;
   Console::WriteLine( Object::ReferenceEquals( p, q ) );
   Console::WriteLine( Object::ReferenceEquals( o, p ) );
}

/*

This code produces the following output.

True
True
False

*/

JScript

import System

class MyClass {

   static function Main() {
      var o = null;
      var p = null;
      var q = new Object();

      Console.WriteLine(Object.ReferenceEquals(o, p));
      p = q;
      Console.WriteLine(Object.ReferenceEquals(p, q));
      Console.WriteLine(Object.ReferenceEquals(o, p));
   }
}

MyClass.Main();

/*

This code produces the following output.

True
True
False

*/

Platforms

Windows 7, Windows Vista, Windows XP SP2, Windows XP Media Center Edition, Windows XP Professional x64 Edition, Windows XP Starter Edition, Windows Server 2008 R2, Windows Server 2008, 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, Zune

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

.NET Framework

Supported in: 3.5, 3.0, 2.0, 1.1, 1.0

.NET Compact Framework

Supported in: 3.5, 2.0

XNA Framework

Supported in: 3.0, 2.0, 1.0

Reference