C# Func <> argument types

Question

Im trying "Func" delegation.

    Func<int, string[], bool>(myFunc); //works OK
    Func<string[], bool>(myFunc); //Exception ???

Unhandled Exception: System.ArgumentException: Object of 'System.String'cannot be converted to type 'System.String[]'. Looks like "Func" doesn't like argument type "string[]" ?!?"

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            Dictionary<string, Delegate> commandHash = new Dictionary<string, Delegate>();
            commandHash.Add("Test", new Func<string[], bool>(Test));
            string[] str = { "justtext" };

            try
            {

                commandHash["Test"].DynamicInvoke(str);
            }
            catch
            {
                Console.WriteLine("Exception");
            }

        }
        static  bool Test(string[] s)
        {
            Console.WriteLine("Test");

            return true;
        }
    }
}


// CODE which works OK, what Im missing ?!

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            Dictionary<string, Delegate> commandHash = new Dictionary<string, Delegate>();
            commandHash.Add("Test", new Func<string[], int, bool>(Test));
            string[] str = { "justtext" };

            try
            {

                commandHash["Test"].DynamicInvoke(str, 1);
            }
            catch
            {
                Console.WriteLine("Exception");
            }

        }
        static  bool Test(string[] s, int i)
        {
            Console.WriteLine("Test");

            return true;
        }
    }
}

No; it means you're trying an invalid cast. Look at the stack trace — SLaks, Mar 04 '15 at 18:02
Please post code that demonstrate the exception. Code in current sample can't even compile, so there is no way to see why you are getting run-time exception. — Alexei Levenkov, Mar 04 '15 at 18:23

Matthew · Accepted Answer · 2015-03-04T21:12:57.547

1

DynamicInvoke parameter uses the params object[] definition.

This means when you are passing an array of string[] to this function, each entry in the array of strings is a new parameter.

You are getting an exception because you cant cast a string to string[];

What you need to do is call DynamicInvoke like this.

commandHash["Test"].DynamicInvoke(new object[] { str });

edited Mar 04 '15 at 21:12

answered Mar 04 '15 at 21:06

Matthew

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C# Func <> argument types

1 Answers1