Delegates - Action vs Func vs Predicate

Introduction

 

As we know, a delegate is a pointer to a method. In this article, we will see 3 types of pointers, listed below:

• Action
• Func
• Predicate

Action

 

Action is a delegate, it can be used to point a method that has no return type. (i.e. return type will be void.)

 

Below is the sample code of using an Action:

using System;

namespace Delegates.Samples.Demo
{
    class Program
    {
        static void Main(string[] args)
        {
            Action<string> log = new Action<string>(LogInfo);
            log.Invoke("Hi ALL");
            Console.ReadLine();

        }

        static void LogInfo(string message)
        {
            Console.WriteLine(message);
        }
    }
}

Below is the output snap of the Action delegate:

 

 

 

Func

 

Func is a delegate, we can define type(s) of input params, and at the end, we can write the output param type.

 

Below is the sample code of using Func:

using System;

namespace Delegates.Samples.Demo
{
    class Program
    {
        static void Main(string[] args)
        {
            Func<int, int, int> addFunc = new Func<int, int, int>(Add);
            int result = addFunc(3, 4);
            Console.WriteLine(result);
            Console.ReadLine();

        }
        static int Add(int a, int b)
        {
            return a + b;
        }
    }
}

Below is the output snap of the Func delegate:

 

 

Predicate

 

Predicate will always return bool, which accepts any type of parameter as its input.

 

Below is the sample code of using Func:

using System;

namespace Delegates.Samples.Demo
{
    class Program
    {
        static void Main(string[] args)
        {
            Predicate<int> IsEven = new Predicate<int>(IsEvenNumber);
            Console.WriteLine(IsEven(10));
            Console.WriteLine(IsEven(1567));
            Console.ReadLine();

        }
        static bool IsEvenNumber(int number)
        {
            return number % 2 == 0;
        }
    }
}

Below is the output snap of the Predicate delegate:

 

 

Summary

 

In this article, we saw the usage of 3 types of delegates. For your reference, I uploaded the project file. You can download and check it out.