using System;

public class Program

{

    public static void Main()

    {

        var a = "foo";

        var b = "foo";

        var c = String.Copy(a);

        Console.WriteLine("a: " + a);

        Console.WriteLine("b: " + b);

        Console.WriteLine("c: " + c);

        Console.WriteLine("a ref= b: " + String.ReferenceEquals(a, b));

        Console.WriteLine("a equals b: " + String.Equals(a, b));

        Console.WriteLine("a ref= c: " + String.ReferenceEquals(a, c));

        Console.WriteLine("a equals c: " + String.Equals(a, c));

        Console.WriteLine("b ref= c: " + String.ReferenceEquals(b, c));

        Console.WriteLine("b equals c: " + String.Equals(b, c));

        a = "bar";      

        Console.WriteLine("a: " + a);

        Console.WriteLine("b: " + b);

        Console.WriteLine("c: " + c);

        Console.WriteLine("a ref= b: " + String.ReferenceEquals(a, b));

        Console.WriteLine("a equals b: " + String.Equals(a, b));

        Console.WriteLine("a ref= c: " + String.ReferenceEquals(a, c));

        Console.WriteLine("a equals c: " + String.Equals(a, c));

        Console.WriteLine("b ref= c: " + String.ReferenceEquals(b, c));

        Console.WriteLine("b equals c: " + String.Equals(b, c));

    }

}