Func and Action

 
delegate TResult Func <out TResult>  ();
delegate TResult Func <in T, out TResult>  (T arg);
delegate TResult Func <in T1, in T2, out TResult>  (T1 arg1, T2 arg2);

... and so on, up to T16

delegate void Action  ();
delegate void Action <in T>  (T arg);
delegate void Action <in T1, in T2>  (T1 arg1, T2 arg2);

... and so on, up to T16

 
using System;
class Test
{
    static void output(int[] intArray, Action<int> p)
    {
        foreach (int i in intArray)
        {
            p(i);
        }
    }
    static void consolePrinterInt(int i)
    {
        Console.WriteLine(i);
    }
    static void Main()
    {
        Action<int> p = consolePrinterInt;
        int[] intArray = new int[] { 1, 2, 3 };
        output(intArray, p);
    }
}