Difference between ref and out keyword

Example: ref keyword

 

    Initialization not must to inside in method.

    Before calling a method must be Initialized the values of variables.

namespace ConsoleApplication1

{

    public class swapClass 

    {

        // Swap using third variable, ref keywords

        public  void swapMethod(ref int a, ref int b)

        {

            // Initialization not must to inside in method.

            // before calling a method must be Initialized the values of variables.

         

            int Temp;

            Temp = a;

            a = b;

            b = Temp;

        }

    }

    public class Program

    {

        static void Main(string[] args)

        {

            swapClass obj = new swapClass();

            // using ref Keywords

            int a=10;

            int b=20;         

            obj.swapMethod(ref a, ref b);

            Console.WriteLine("After Swap A= " + a + " B =" + b);

            Console.ReadLine();

        }

    }

}

Example: Out keyword

     Initialization must to inside in method

     Before calling a method maybe initialized or not the values of variables.

namespace ConsoleApplication1

{

    public class swapClass 

    {

        // Swap without using third variable, out keywords

        public void swapWTMethod(out int c, out int d)

        {

          // Initialization must to inside in method

          // before calling a method maybe Initialized or not the values of variables.

            c = 10;

            d = 20;

            c = c + d;

            d = c - d;

            c = c - d;         

        }

    }

    public class Program

    {

        static void Main(string[] args)

        {

            // using out keywords

            int c;

            int d;

            obj.swapWTMethod(out c, out d);

            Console.WriteLine("Before SwapWT C= " + c + " D =" + d);           

            Console.ReadLine();

        }

    }

}