How to swap two strings

using System;

class SwappinStrings

{

    static void SwapStrings(ref string s1, ref string s2)

    // The string parameter x is passed by reference.

    // Any changes on parameters will affect the original variables.

    {

        string temp = s1;

        s1 = s2;

        s2 = temp;

        Console.WriteLine("Inside the method: {0}, {1}", s1, s2);

    }

    public static void Main()

    {

        string str1 = "John";

        string str2 = "Smith";

        Console.WriteLine("Inside Main, before swapping: {0} {1}", str1, str2);

        SwapStrings(ref str1, ref str2); // Passing strings by reference

        Console.WriteLine("Inside Main, after swapping: {0}, {1}", str1, str2);

    }

}