static void Main(string[] args)

    {

        int arg;

​

        // Passing by value.

        // The value of arg in Main is not changed.

        arg = 4;

        squareVal(arg);

        Console.WriteLine(arg);

        // Output: 4

​

        // Passing by reference.

        // The value of arg in Main is changed.

        arg = 4;

        squareRef(ref arg);

        Console.WriteLine(arg);

        // Output: 16 

          static void squareVal(int valParameter)

        {

            valParameter *= valParameter;

        }

​

        // Passing by reference

        static void squareRef(ref int refParameter)

        {

            refParameter *= refParameter;

        }

    }