Use of 'ref' keyword in C# [duplicate]

Answer 1

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Diagnostics;

namespace InOutRef
{
    static class InOutRef
    {
        public static void In(int i)
        {
            Console.WriteLine(i);
            i=100;
            Console.WriteLine(i);
        }
        public static void Ref(ref int i)
        {
            Console.WriteLine(i);
            i=200;
            Console.WriteLine(i);
        }
        public static void Out(out int i)
        {
            //Console.WriteLine(i); //Error Unsigned Ref
            i=300;
            Console.WriteLine(i);
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            int i = 1;
            InOutRef.In(i); //passed by value (in only)
            Debug.Assert(i==1);
            InOutRef.Ref(ref i); //passed by ref (in or out)
            Debug.Assert(i == 200);
            InOutRef.Out(out i); //passed by as out ref (out only)
            Debug.Assert(i == 300);
        }
    }
}

I can't be any more literal on my answer. The code will not remember reference chanages such as the classic Java swap question when using in. However, when using ref, it will be similar to VB.NET as it will remember the changes in and out. If you use the out parameter it means that it must be declared before you return (this is enforced by the compiler).

Output:
1                                  //1 from main 
100                                //100 from in
1                                  //1 is NOT remembered from In
200                                //200 from ref
//should be 200 here but out enforces out param (not printed because commented out)
300                                //300 is out only
Press any key to continue . . .