using System;

public class Program

{

    public static void Main()

{

    var myString = "initial value";

    MyMethod(myString, MyRefMethod(ref myString));

}

​

public static string MyRefMethod(ref string str)

{

    Console.WriteLine("Method call start");

    str = "new value";

    Console.WriteLine("Method call end");

    return "this variable doesn't really matter for this example";

}

​

public static void MyMethod (string importantString, string doesntMatterString)

{

    Console.WriteLine(importantString);

}

}