class Program
    {
        static void Double(ref int number)
        {
            Console.WriteLine($"Inside function => Value before change: {number}");
            number *= 2;
            Console.WriteLine($"Inside function => Value after change: {number}");
        }

        static void Main(string[] args)
        {
            int value = 5;
            Console.WriteLine($"Inside main => Value before function call: {value}");
            Double(ref value);
            Console.WriteLine($"Inside main => Value after function call: {value}");

            Console.ReadLine();
        }
    }