Why can't a delegate refer to a non-static method when used in a static method?

Question

Why do I need the STATIC function when using delegates in C #?

class Program
{
    delegate int Fun (int a, int b);
    static void Main(string[] args)
    {
        Fun F1 = new Fun(Add);
        int Res= F1(2,3);
        Console.WriteLine(Res);
    }

   **static public int Add(int a, int b)** 
    {
        int result;
        result = a + b;
        return result;
    }
}

Answer 1

This is not "necessary." But your main method static, therefore, it cannot call the method static. Try something like this (this is not a good way to do something - you really need to create a new class, but it does not change your choice much):

class Program 
{ 
    delegate int Fun (int a, int b); 
    void Execute()
    {
       Fun F1 = new Fun(Add); 
       int Res= F1(2,3); 
       Console.WriteLine(Res); 
    }

    static void Main(string[] args) 
    { 
        var program = new Program();
        program.Execute();
    } 

    int Add(int a, int b)
    { 
        int result; 
        result = a + b; 
        return result; 
    } 
}

Answer 2

Your function must be static because you are calling the static Main method. You can make the method non-static:

class Program
{
    delegate int Fun (int a, int b);
    static void Main(string[] args)
    {
        Program p = new Program();       // create instance of Program
        Fun F1 = new Fun(p.Add);         // now your non-static method can be referenced
        int Res= F1(2,3);
        Console.WriteLine(Res);
    }

    public int Add(int a, int b)
    {
        int result;
        result = a + b;
        return result;
    }
}

Answer 3

, - , . "", .

Answer 4

, . , . :

static void Main(string[] args)
{
    int Res = Add(3, 4);
    Console.WriteLine(Res);
}

public int Add(int a, int b)
{
    int result;
    result = a + b;
    return result;
}

, , :

class MyClass
{
    public MyClass()
    {
        Fun F1 = new Fun(Add);
        int Res = F1(2, 3);
        Console.WriteLine(Res);
    }

    public int Add(int a, int b)
    {
        int result;
        result = a + b;
        return result;
    }
}

.