Delegates in C#: What They Are and How to Use Them?

Delegates in C#/.NET seemed like an “extra” thing when I first learned about them. But, as I started practicing more and more and started doing small projects, delegates became my true friends.

That is why we will dive into one of the most powerful features of C#: “Delegates.” Delegates are a way to define a method signature, allowing you to pass methods as parameters or store them as variables. In this post, I’ll cover what delegates are, how to use them, and some best practices to remember.

What are Delegates in C#?

At its simplest, a delegate is a type that represents a method signature. Delegates allow you to pass methods as parameters or store them as variables, which can be useful in various scenarios.

Here’s a basic example of a delegate:

delegate void MyDelegate(string message);

In this example, we’ve defined a delegate called MyDelegate which represents a method that takes a string parameter and returns void. Now we can create variables of type MyDelegate and assign methods to them:

void PrintMessage(string message)
{
    Console.WriteLine(message);
}
MyDelegate delegate1 = new MyDelegate(PrintMessage);
delegate1("Hello, world!");

In this example, we’re creating a new variable called delegate1 of type MyDelegate and assigning it to the PrintMessage method. We can then call the delegate and pass it a string parameter to invoke the method. To test out this code, you can use the following code snippet:

namespace NaveedUlHaq{
    class GenDel{
        delegate void MyDelegate(string message);
        public static void PrintMessage(string message)
            {
             Console.WriteLine(message);
            }
        static void Main(){
            MyDelegate delegate1 = PrintMessage;
            delegate1("Hello, world!");
        }      
    }
}

When this code is executed, it produces the following outcome:

Why do We Use Delegates in C#?

Delegates are particularly useful in event-driven programming, where an event can trigger one or more methods to execute. Normally, methods in C/.NET cannot be used/passed a parameter upon the occurrence of a specific event.

However, with the help of Delegates, that becomes possible. This means that making applications with user interaction is going to require you to make use of delegates.

Using Delegates in C#

Now that we’ve defined our delegate, let’s see how we can use it in our code. Here’s an example of using a delegate to pass a method as a parameter:

void DoSomething(string message, MyDelegate callback)
{
    Console.WriteLine($"Doing something with message: {message}");
    callback(message);
}
DoSomething("Hello, world!", delegate1);

In this example, we’re defining a method called DoSomething that takes a string parameter and a MyDelegate parameter called callback. We’re then calling DoSomething and passing it the string “Hello, world!” and our delegate1 variable as the callback parameter. Inside DoSomething, we’re printing a message and then invoking the callback method with the string parameter.

Best Practices for Using Delegates

Here are some best practices to keep in mind when using delegates in your C# code:

1. Use meaningful names for your delegates. This makes your code more readable and self-documenting.
2. Keep your delegate signatures simple and focused. Delegates with complex signatures can be difficult to work with and maintain.
3. Use delegates to pass methods as parameters or store them as variables. This can make your code more flexible and reusable.

Wrap up

With these simple steps and examples, you can start using delegates in your C# code to write more flexible and reusable code. Delegates are a powerful tool that can make your code more modular and easier to maintain, especially in an event-driven application. Therefore, practice delegates by doing small projects. As we already know, no application is complete with the event’s occurrence, either caused by the user’s interaction or by the completion of a process.