Delegates Program

I made a very simple program of Delegates. I have no idea why is it showing error, even though I compared it with the one given in MSDN library, its same like the one in MSDN, still not getting compiled..the error says- "The name 'Add' does not exist in the current context "and same for the other method.. Subtract. Please help me find what is the problem..

namespace DelegatePrac
{   
   public delegate void One(int a, int b); 
    public class Some
     {
  static void Add(int a, int b)
       { 
      int c = a + b;    Console.WriteLine("{0}",c);
       }
       static void Subtract(int a, int b)
       { int c = a - b;  Console.WriteLine("{0}",c);
       }

    }

    class Program
    {
        static void Main(string[] args)
        {
            One o1,o2;
            o1 = Add;//gives error here
开发者_开发知识库            o2 = Subtract;//and here!!
            o1(33,44);
            o2(45, 15);
         Console.ReadLine();
        }
    }
}

I was following this link- http://msdn.microsoft.com/en-us/library/ms173175.aspx

Thanks

You should see a compiler message:

The name 'Add' does not exist in the current context

which tells you that it has no clue which Add method you are talking about; Add is a static method in Some - so you need:

o1 = Some.Add;
o2 = Some.Subtract;

static methods aren't globally available; you can access static methods from the current type (and from base-types) via just their name, but if it is an unrelated type you need to qualify it with the declaring-type.

At this point it will give you a compiler error:

'DelegatePrac.Some.Add(int, int)' is inaccessible due to its protection level

which hints that it is a private method; so add public (or internal) to them:

public static void Add(int a, int b) {...}

Have you tried exchanging those two lines with errors with this?

o1 = Some.Add;
o2 = Some.Subtract;

You haven't posted your error, but the class Program has no Add or Subtract methods, so I guess your error is that Add and Subtract is not found.

EDIT

And as ssd said in his answer, the static methods have to be public to be accessed from outside the class. You have not specified any access modifier, and thereby the methods will default to private.

Two things:

• You need to mark Add and Subtract as public.
• They are not part of class Program. So while using them in other classes than Some, you need to specify they are part of Some by using Some.Add and Some.Subtract.

Corrected Code:

namespace DelegatePrac
{   
    public delegate void One(int a, int b); 
    
    public class Some
    {
        public static void Add(int a, int b)
        { 
            int c = a + b;    Console.WriteLine("{0}",c);
        }
       
        public static void Subtract(int a, int b)
        { 
            int c = a - b;  Console.WriteLine("{0}",c);
        }
    }

    class Program
    {
        static void Main(string[] args)
        {
            One o1,o2;
            o1 = Some.Add;//gives error here
            o2 = Some.Subtract;//and here!!
            o1(33,44);
            o2(45, 15);
            Console.ReadLine();
        }
    }
}