C# delegates

In C#, a delegate is a pointer to a method. That means, a delegate holds the address of a method which can be called using that delegate.

Let's learn how we can define and execute a delegate.

Define a delegate

We define a delegate just like we define a normal method. That is, delegate also has a return type and parameter. For example,

public delegate int myDelegate(int x);


  • delegate - a keyword
  • int - return type of delegate
  • myDelegate - delegate name
  • int x - parameter that the delegate takes

Any method from any accessible class or struct that matches the delegate signature can be assigned to the delegate.

Note: A delegate is also called type-safe pointer.

Instantiate a delegate

Suppose, we have a method named calculateSum() whose signature is the same as myDelegate.

To create an instance of myDelegate, we pass a method name as a parameter. For example,

myDelegate d1 = new myDelegate(calculateSum);

Example: Calling a Method Using delegate

using System;
using System.Collections.Generic;
class Program
    // define a method that returns sum of two int numbers 
    static int calculateSum(int x, int y)
        return x + y;

// define a delegate public delegate int myDelegate(int num1, int num2);
static void Main() {
// create an instance of delegate by passing method name myDelegate d = new myDelegate(calculateSum);
// calling calculateSum() using delegate int result = d(5, 6);
Console.WriteLine(result); } }



In the above example, we have created an instance of myDelegate d) and passed calculateSum() as a parameter.

Here, we have called the calculateSum() method by passing 5 and 6 as parameters values in d.

Use of C# delegates

We can use delegates to:

  • promote reusability of code and implement flexibility
  • notify which method to call when an event is triggered
  • define callback methods

Frequently Asked Questions

Multicast Delegate in C#

The multicast delegate is used to point to more than one method at a time. We use += operator to add methods to delegate. For example,

using System;
class Program
    // method that prints sum of two int numbers 
    public void sum(int x, int y)
        Console.WriteLine("Sum is: " + (x + y));

    // method that prints difference of two int numbers 
    public void difference(int x, int y)
        Console.WriteLine("Difference is: " + (x - y));

    // define a delegate of int type 
    public delegate void myDelegate(int num1, int num2);

    static void Main()
        // instance of Program class
        Program obj = new Program();

        // create an instance of delegate and
        // pass sum method as a parameter 
        myDelegate d = new myDelegate(obj.sum);

// multicast delegate // calls difference() method d += obj.difference;
// pass values to two methods i.e sum() and difference() d(6, 5); } }


Sum is: 11
Difference is: 1
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