using System;

​

public class Program

{

    public static void Main()

    {

        Console.WriteLine("Hello Swapsies");

        int x = 42;

        int y = 5;

        Test.TestSwap(x, y);

        Test.TestSwap(42, 5);

        Test.TestSwap(int.MaxValue, 1);

        Test.TestSwap(int.MaxValue, int.MaxValue);

        Test.TestSwap(0, int.MaxValue);

        Test.TestSwap(0, 0);

    }

​

    public static void Swap(ref int x, ref int y)

    {

        x = x * y;

        y = x / y;

        x = x / y;

    }

    public static void Swap2(ref int x, ref int y)

    {

        x = x + y;

        y = x - y;

        x = x - y;

    }

    public static void Swap3(ref int x, ref int y)

    {

        x = x + y;

        y = x + y;

        x = x + y;

    }

}

​

public static class Test

{

    public static void TestSwap(int x, int y)

    {

        var x0 = x;

        var y0 = y;

        Console.Write("x={0} \r y={1} \r", x, y);

        Program.Swap2(ref x, ref y);

        Console.Write("--> x={0} \r y={1} \r", x, y);

        Console.WriteLine( (y == x0 && x == y0) ? "OK!" : "FAIL" );

    }

}