How to use the Func type in C#

To make using delegates easier, Microsoft introduced a new generic type, Func.

Main features:

• The Func encapsulates callable code. 
• It can take 1 to 16 input parameters.
• The last prameter is the return type.

There, easy.

As an example, Func<int, int, bool> takes two integers as input and will return a bool.

private static void PlayWithFunc()

{

// First two params are input, last param is output

Func<int, int, int> addemup = (x,y) => x+y;

Console.WriteLine( addemup(2, 3));

// Note that with the single input param, x is in brackets: (x)

Func<int, bool> notZero = (x) => x!=0;

Console.WriteLine( notZero(1) );

// Note also,that with the single input param, x is NOT brackets: x

Func<int, int> sqr = x => x*x;

Console.WriteLine( sqr(2) );

Console.ReadLine();

}

Note that if you have 2 or more parameters in the lambda expression you must have parenthesis. If you have one parameter the parameters are optional.


Action

Ah, but what happens if you don't want to return a value. 

The Action type is the same as Func, except it returns void.

Action <string> printToConsole = s => Console.WriteLine("The string is: " + s);

printToConsole ("Hi there");

Console.ReadLine();