C# 4.0 : Named arguments and Optional parameter

Along with Optional Parameter C# 4.0 introduces a new feature of Named parameters as well, where we can provide a value of parameters with their name. We can pass arguments in any order, there is no need to remember the order of parameters.

Example1: Named Parameters

public void Hello(string strGreeting, string strWin)

{

     Console.WriteLine(strGreeting + “ ” + strWin);

}

Irrespective of the order of parameters, output of both the method calls will be same here.

Hello(strGreeting: "Hello!", strWin: "India");

Hello(strWin: "India", strGreeting: "Hello!");

Hello("Hello!", strWin: "India");

Output: 

Hello! India

Hello! India

Example2: Named and Optional

Named arguments are generally used with optional parameters.

public void Hello(string strGreeting = "Hello!", string strWin= "Winshuttle")

{

       Console.WriteLine(strGreeting + " " + strWin);

}

Hello();

Hello("Hello!");

Hello("Hello!", "Winshuttle");

Hello(strGreeting: "Hello!", strWin: "Winshuttle");

Hello(strWin: "Winshuttle", strGreeting: "Hello!");

Hello("Hello!", strWin: "Winshuttle");

Output: 

Hello! Winshuttle

Hello! Winshuttle

Hello! Winshuttle

Hello! Winshuttle

Hello! Winshuttle

Note:

• Named argument must come after all positional parameters.
• These both are useful when we call COM API’s.
• We can omit method overloads using these features.