CODEWITHSUNDEEP
c#delegates
user6478007
user6478007

Reputation:

delegate giving error the name 'ad1' does not exist in current context

i have created a class person which is having functions add,sub,mul and mytest where i am passing my delegate reference

and in static void main i want if

DateTime.Now.Hour<12 it should call add if DateTime.Now.Hour<20 it should call sub.

but i am getting error

'ad1' does not exist in current context

 class person
 {
    public void add(int x,int y)
    {
        Console.WriteLine(x+y);
    }
    public void sub(int x,int y)
    {
        Console.WriteLine(x-y);
    }
    public void mul(int x,int y)
    {
        Console.WriteLine(x*y);
    }
    public void test(mydel ad1)
    {
        ad1(2, 3);
    }
 }
 class Program
 {
     static void Main(string[] args)
     {
         person p = new person();
         if(DateTime.Now.Hour<12)
         {
             mydel ad1 = p.add;
         }
         else if(DateTime.Now.Hour<20)
         {
             mydel ad1 = p.sub;
         }
         p.test(ad1);      
     }
 }

Upvotes: 0

Views: 365

Answers (2)

loneshark99
loneshark99

Reputation: 734

class person
    {
        public void add(int x, int y) => Console.WriteLine(x + y);
        public void sub(int x, int y) => Console.WriteLine(x - y);
        public void mul(int x, int y) => Console.WriteLine(x * y);
        public void test(Action<int, int> ad1) => ad1(2, 3);

    }
    class Program
    {
        static void Main(string[] args)
        {
            person p = new person();
            Action<int, int> action = (x, y) => {};
            if (DateTime.Now.Hour < 12)
            {
                action = p.add;
            }
            else if (DateTime.Now.Hour < 20)
            {
                action = p.sub;
            }
            p.test(action);
        }
    }

Upvotes: 0

Ofir Winegarten
Ofir Winegarten

Reputation: 9365

ad1 is declared inside the if block in the Main method and doesn't exists outside the if scope.

I don't think you need this variable at all just call directly from within the if:

static void Main(string[] args)
{
    person p = new person();
    if(DateTime.Now.Hour<12)
    {
        p.test(p.add);
    }
    else if(DateTime.Now.Hour<20)
    {
        p.test(p.sub);
    }
}

This will also ensure that when Hour > 20 nothing will be called, and you won't get a null exception.

If you do however choose to use this variable, define it before the if (and assign it with null) and ensure it's not null before you use it.

Upvotes: 0

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