using System;

​

class ParamMethod

{

    public void Method1(ref int x, ref int y)

    { // x ref 100, y ref 200

        Console.WriteLine($"2-Inside the method before transformations: x={x} - y={y}");

        int temp = x; // temp=100

        x = y;        // assigned to x the reference of y (200)

        y = temp;     // changed value to the reference of y (100)

        // NO return of values here. 

        // Only an internal modification of reference types

        Console.WriteLine($"3-Inside the method after transformations:  x={x} - y={y}");

    }

​

    static void Main(string[] args)

    {

        // we instantiate the object obj1  (START HERE)

        ParamMethod obj1 = new ParamMethod();

​

        int x = 100; // here x=100 before the invocation of Method1 

        int y = 200; // here y=200 before the invocation of Method1         

        Console.WriteLine($"1-Before method call:                       x={x} - y={y}");

        // invocation of Method1 and passing references of x and y

        obj1.Method1(ref x, ref y);

        // Here x=200 and y=100 

        // because the change of reference to the heap inside 

        // the method also has an influence outside it

        Console.WriteLine($"4-After the method call:                    x={x} - y={y}");

    }

}