ref vs out in C#

Samajh me na aaya kuch .

"Both ref and out are treated differently at run time and they are treated the same at compile time." I think you've got this backwards, they are treated the same at runtime, they are treated differently at compile time! The main differences between ref and out is that with out the compiler requires you to initialize the parameter within the method before you use it, otherwise you'll get CS0269, and if you don't assign anything you'll get CS0177. With ref the compiler requires you to pass an initialized variable, otherwise you'll get CS0165. In the debugger you can see that an out parameter has the value you pass to it before you initialize it it in the method, it is only the compiler that doesn't allow you to use it.

Ref tells the compiler that the object is initialized before entering the function, while out tells the compiler that the object will be initialized inside the function.

Nice article.I have one question : if we have one function then which one we should use preferably ref or out...!! And why ?

Good explanation.

Nicely done. I still have doubt, why do I need to initialise out parameter inside the method, what purpose does it serves?

I believe most important use case of out parameter is to return multiple values from a single called method. Whereas ,In normal function call ( without Out parameter), We can return only one value. Example from Microsoft documentation will make the concept more clear to you: void Method (out int answer, out string message, out string stillNull) { answer = 44; message = "I've been returned"; stillNull = null; } int argNumber; string argMessage, argDefault; Method(out argNumber, out argMessage, out argDefault); Console.WriteLine(argNumber); Console.WriteLine(argMessage); Console.WriteLine(argDefault == null); // The example displays the following output: // 44 // I've been returned // True Notice that we returned multiple values from Method with different data types. This use case is widely used.

Better Example to understand Ref and out using System; public class Program { public static void Main() { int i; // we need not initialize for out int j=20; string test = GetNextNameByOut(out i); string testref = GetNextNameByRef(ref j); Console.WriteLine("Current value of integer i:" + i.ToString()); // Current value of integer i:10 Console.WriteLine("Current value of integer i:" + test); //Current value of integer i:Next-10 Console.WriteLine("Return value of out " + j.ToString()); //Return value of out 20 Console.WriteLine("Return value of ref " + testref);//Return value of ref Next-20 } public static string GetNextNameByOut(out int id) { id = 10; //complusary initialization before using string returnText = "Next-" + id.ToString(); return returnText; } public static string GetNextNameByRef(ref int id) { string returnText = "Next-" + id.ToString(); return returnText; } }

A real time example please. why and when we use these keywords.

In case of ref

Wrong (It is not compulsory to initialize a parameter value before using it in a calling method.)

Excellent explanation..

Public static string GetNextNameByOut(out int id) { id = 1; string returnText = "Next-" + id.ToString(); return returnText; } void Main() { int i = 8; string test = GetNextNameByOut(out i); } In following code 'Out' code is calling from main function to calling method GetNextNameByOut(out int id){ id=1 you initialized. when ever we passing any value for it (out i) id value changed into 1, then why we have to call out key word? Please give assist..

Great article. Thank you very much. keep it up

nice sir

nice explained

nice article