CALL BY VALUE &CALL BY REFERENCE

Call by value is when you create a local copy of the variable.  This is usually only a good idea for small variables that you will not need to change.

Call by reference occurs when you pass the address of the variable to the function (receiving a pointer or reference).  It is useful if you need to be able to change the  variable's value in the function, or if the variable is extremely large and passing it by value would be extremely inefficient (because of the cost of creating a local copy).

Call by value :

using System;

namespace call_by_value

{

          class c

          {

                    public int x=100;

                    public void method(int x)

                    {

                              x=x+x;

                              Console.WriteLine("within the method : "+x.ToString());

                    }

                    public static void Main()

                   {

                              c obj=new c();

                              Console.WriteLine(obj.x);

                              obj.method(obj.x);

                              Console.WriteLine("after coming out of the method : "+obj.x);

                              Console.ReadLine();

                    }

          }

}

Call by Reference

using System;

namespace call_by_reference

{

          class c

           {

                    public int x=100;

 

 public void method(ref int x)

                    {

                              x=x+x;

                              Console.WriteLine("within the method : "+x.ToString());

                    }

                    public static void Main()

                    {

                              c obj=new c();

                              Console.WriteLine(obj.x);

                              obj.method(ref obj.x);

                              Console.WriteLine("after coming out of the method : "+obj.x);

                              Console.ReadLine();

                    }

          }

}