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What is the difference between “==” and .Equals()?

, 26 Apr 2013 CPOL 45.1K 9
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When we create any object there are two parts to the object one is the content and the other is reference to that content.So for example if you create an object as shown in below code:-“.NET interview questions” is the content.“o” is the reference to that content.object o = ".NET Interview questions
When we create any object there are two parts to the object one is the content and the other is reference to that content.
So for example if you create an object as shown in below code:-
  1. “.NET interview questions” is the content.
  2. “o” is the reference to that content.
object o = ".NET Interview questions"; 
 “==” compares if the object references are same while “.Equals()” compares if the contents are same.
So if you run the below code both “==” and “.Equals()” returns true because content as well as references are same.

object o = ".NET Interview questions";
object o1 = o;
Console.WriteLine(o == o1);
Console.WriteLine(o.Equals(o1));
Console.ReadLine();

True

True


Now consider the below code where we have same content but they point towards different instances. So if you run the below code both “==”   will return false and “.Equals()”  will return true.

 

object o = ".NET Interview questions";
object o1 = new string(".NET Interview questions".ToCharArray());
Console.WriteLine(o == o1);
Console.WriteLine(o.Equals(o1));
Console.ReadLine();

False

True


When you are using string data type it always does content comparison. In other words you either use “.Equals()” or “==” it always do content comparison.
 

You can also watch the following video of the above explanation at C# interview questions and answers :- Difference between "==" and ".Equals()" ?

<OBJECT type="application/x-shockwave-flash" codebase="http://download.macromedia.com/pub/shockwave/cabs/flash/swflash.cab#version=3,0,0,0" WIDTH="640" HEIGHT="360" data="http://www.youtube.com/v/3IReFdq5d7o?version=3&feature=player_detailpage"></OBJECT>

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This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)

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About the Author

Shivprasad koirala
Architect http://www.questpond.com
India India

I am a Microsoft MVP for ASP/ASP.NET and currently a CEO of a small
E-learning company in India. We are very much active in making training videos ,
writing books and corporate trainings. Do visit my site for 
.NET, C# , design pattern , WCF , Silverlight
, LINQ , ASP.NET , ADO.NET , Sharepoint , UML , SQL Server  training 
and Interview questions and answers


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Comments and Discussions

 
GeneralWrong Pin
Sopan Maiti2-Jul-15 20:04
memberSopan Maiti2-Jul-15 20:04 
QuestionDiffcult to understand Pin
madan singh bora26-Jun-15 17:52
membermadan singh bora26-Jun-15 17:52 
QuestionAlways == does not do the content comparison for string Pin
gourav.agrawal28-Jan-15 1:45
membergourav.agrawal28-Jan-15 1:45 
GeneralClear! Pin
nicolas mertens20-Jun-14 1:35
membernicolas mertens20-Jun-14 1:35 
QuestionGood Explanation Pin
Member 1028643326-Feb-14 2:35
memberMember 1028643326-Feb-14 2:35 
GeneralMy vote of 5 Pin
M Rayhan3-Jan-14 17:51
memberM Rayhan3-Jan-14 17:51 
GeneralMy vote of 3 Pin
John Brett28-Apr-13 22:19
memberJohn Brett28-Apr-13 22:19 
GeneralRe: My vote of 3 Pin
Shivprasad koirala2-May-13 19:52
mvpShivprasad koirala2-May-13 19:52 
Generalsmth wrong Pin
mythteria26-Apr-13 21:32
membermythteria26-Apr-13 21:32 
GeneralRe: smth wrong Pin
Shivprasad koirala26-Apr-13 21:54
mvpShivprasad koirala26-Apr-13 21:54 
???? yes it is false....did i say anything different.

Skeet is Skeet...So i am a very small person to contradict him even in dreams.
My book .NET interview questions with 500 mostly asked questions in .NET world .NET Interview questions and answers

GeneralRe: smth wrong Pin
mythteria29-May-13 2:01
membermythteria29-May-13 2:01 
GeneralRe: smth wrong Pin
Member 104448254-Dec-13 12:12
memberMember 104448254-Dec-13 12:12 

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