Difference between Ref and Out in C#

This short article explain what is the difference between out and ref keyword in C#.

This is one of the populate question always ask in forum.

This differs from out parameters, whose arguments do not have to be explicitly initialized before they are passed.

The code sample below will get compilation error “Use of unassigned local variable value”.

 

static void MethodRef(ref int i)

{

    i = 44;

}

static void MethodOut(out int i)

{

    i = 44;

}

static void Main()

{

    int value;

    MethodRef(ref value);

    MethodOut(out value);

}

 

outref

There are many ways to resolve this problem. The simple way will be just initialize the variable value.

static void MethodRef(ref int i)

{

    i = 44;

}

static void MethodOut(out int i)

{

    i = 44;

}

static void Main()

{

    int value = 0;

    MethodRef(ref value);

    MethodOut(out value);

}

About chanmingman

Since March 2011 Microsoft Live Spaces migrated to Wordpress (http://www.pcworld.com/article/206455/Microsoft_Live_Spaces_Moves_to_WordPress_An_FAQ.html) till now, I have is over 1 million viewers. This blog is about more than 50% telling you how to resolve error messages, especial for Microsoft products. The blog also has a lot of guidance teaching you how to get stated certain Microsoft technologies. The blog also uses as a help to keep my memory. The blog is never meant to give people consulting services or silver bullet solutions. It is a contribution to the community. Thanks for your support over the years. Ming Man is Microsoft MVP since year 2006. He is a software development manager for a multinational company. With 25 years of experience in the IT field, he has developed system using Clipper, COBOL, VB5, VB6, VB.NET, Java and C #. He has been using Visual Studio (.NET) since the Beta back in year 2000. He and the team have developed many projects using .NET platform such as SCM, and HR based applications. He is familiar with the N-Tier design of business application and is also an expert with database experience in MS SQL, Oracle and AS 400.
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