Func delegate type in C Sharp (C#)

Introduction

The Func delegate lets you store and use methods that return a value. It helps you pass around small pieces of work easily.

When you want to pass a method as a parameter that returns a result.

When you need to store a method in a variable to call it later.

When you want to write cleaner code by using inline functions.

When you want to use methods with different input types but a return value.

When you want to simplify callbacks that return data.

Syntax

C Sharp (C#)

Func<T1, T2, ..., TResult> variableName = methodName;
// or
Func<T1, T2, ..., TResult> variableName = (parameters) => expression;

Func can have 0 to 16 input parameters.

The last type parameter is always the return type.

Examples

This Func takes one int and returns its square.

C Sharp (C#)

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

This Func takes two int values and returns their sum.

C Sharp (C#)

Func<int, int, int> add = (a, b) => a + b;

This Func takes no input and returns a greeting string.

C Sharp (C#)

Func<string> greet = () => "Hello!";

Sample Program

This program creates a Func that multiplies two numbers. It then calls it with 4 and 5 and prints the result.

C Sharp (C#)

using System;

class Program
{
    static void Main()
    {
        Func<int, int, int> multiply = (x, y) => x * y;
        int result = multiply(4, 5);
        Console.WriteLine($"4 times 5 is {result}");
    }
}

Important Notes

You can use Func to simplify code that needs small reusable methods.

Remember, the last type parameter is always the return type, others are inputs.

Func is built-in and saves you from writing custom delegate types.

Summary

Func stores methods that return a value.

It can have multiple inputs but only one output.

Use it to pass or store small functions easily.