Why does this lambda doesn't work with the delegate?

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What's the problem with the following code?

C#

class Program
    {
        public delegate string ReturnAStringHandler(string s);

        static void Main(string[] args)
        {
            ReturnAStringHandler sh = ReturnAString;
            ReturnAStringHandler sh2 = () => sh("Hello"); 

            

        }

        public static string ReturnAString(string s)
        {
            return s;
        }
    }

The problem is at this line:

C#

ReturnAStringHandler sh2 = () => sh("Hello");

The compiler says: "Delegate Program.ReturnAStringHandler does not take 0 arguments"

EDIT: Oooooh. It's the signature... Sorry for the stupid question........

What I have tried:

I've tried to understand what is exactly happening.

Posted 23-Mar-18 20:30pm

The_Unknown_Member

Updated 23-Mar-18 20:45pm

v4

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RickZeeland 24-Mar-18 4:44am

Not a stupid question at all, I still find lambdas hard to work with, but that's probably because I'm an old fart who can't get used to "new style" programming :)

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OriginalGriff · Answer 1 · 2018-03-23T20:46:00

Quote:
EDIT: Oooooh. It's the signature... Sorry for the stupid question........

It is indeed!

For the benefit of others with a similar problem, the sh2 declaration requires a parameter:

C#

ReturnAStringHandler sh = ReturnAString;
ReturnAStringHandler sh2 = (x) => sh(x);

Console.WriteLine(sh2("Hello"));