What is Delegates in C# .NET?

What is Delegate?

Delegates are the pointers to the methods. This means They are holding the address of a method, and we can call those methods by calling the delegate. We can also call multiple methods by calling only one delegate.

In simpler terms, think of a delegate as a "method pointer" or a "method reference." It's an object that can hold a reference to a method, including information about the method's return type and parameter types. This allows you to create instances of delegate types and associate them with methods. Then, you can invoke the referenced methods indirectly through the delegate instances.

Steps to define Delegate

1. Choose the Signature: Decide on the signature of the methods that the delegate will reference. The signature includes the return type and parameter types of the methods.
2. Declare the Delegate Type: Use the delegate keyword to declare the delegate type. The delegate type serves as a blueprint for methods that can be assigned to it.
3. Create Delegate Instances: Create instances of the delegate type and associate them with methods that match the delegate's signature.
4. Invoke the Delegate: Use the delegate instances to indirectly call the associated methods.

How to Define Delegate?

We are defining a delegate just like a method without a body.

delegate int MathOperation(int a, int b);

In this example, our delegate takes two parameters and returns an integer.

How To use a delegate?

Firstly, we need to create an object from our delegate and pass the method that it points to. For instance, let's assume we have a method that it calls “Multiply” as below.

 static int Multiply(int a, int b) {
        return a * b;
    }

Create delegate instances

  MathOperation add = (x, y) => x + y;
  MathOperation subtract = (x, y) => x - y;

Invoke the delegates

        int result1 = add(5, 3);       // result1 = 8
        int result2 = subtract(8, 2); // result2 = 6
        int result3 = multiply(4, 3); // result3 = 12

        Console.WriteLine("Result1: " + result1);
        Console.WriteLine("Result2: " + result2);
        Console.WriteLine("Result3: " + result3);

Note. We can use delegates only with the methods that have the same return type and parameter.

Conclusion

delegates in C# serve as powerful connectors between methods and the broader programming framework. They introduce a level of abstraction by allowing methods to be treated as entities that can be assigned, passed, and invoked dynamically. Through delegate declarations, instances, and method associations, developers gain a versatile tool for creating flexible and modular code. Delegates find extensive use in scenarios like event handling, callback mechanisms, and asynchronous programming, enhancing the responsiveness and extensibility of applications.