Delegates and Callback

Question

Hi Friends. I was wondering why do I need a Delegate Callback if I can just call the method the Delegate points to in my Method? I dont understand how using a delegate makes your method more dynamic.

Answer 1

Hi,@Ronald Rex. Welcome Microsoft Q&A. Delegates in C# provide a way to represent a reference to a method, similar to function pointers in other programming languages. They allow you to pass methods as arguments to other methods or store them as variables, making your code more flexible and dynamic. This is particularly useful when you want to decouple the calling code from the implementation of the method, enabling you to change the behavior of a method at runtime or plug in different implementations without modifying the calling code.

Here is an example to understand the concept:

Suppose you have a simple calculation method that adds two numbers:

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

Now, you want to create a method that performs some additional operations before or after calling the Add method. One way to do this is by using a delegate callback:

public delegate int CalculationDelegate(int a, int b);

public int PerformCalculation(int a, int b, CalculationDelegate calculationMethod)
{
    // Additional operations before calling the calculation method
    int result = calculationMethod(a, b);
    // Additional operations after calling the calculation method
    return result;
}

With this approach, you could pass the Add method as a delegate to PerformCalculation, like this:

int sum = PerformCalculation(5, 3, Add);

Now, PerformCalculation will execute the Add method and handle any additional operations you might have defined within it. However, you can also pass other calculation methods that follow the same signature as Add, and PerformCalculation will work with them without any modifications.

For example, let's say you have another calculation method called Multiply:

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

You could use the same PerformCalculation method to work with Multiply:

int product = PerformCalculation(5, 3, Multiply);

By using delegates, you can easily switch between different calculation methods without having to modify the PerformCalculation method. This decoupling of the calling code and the implementation provides flexibility and reusability, making your code more dynamic and easier to maintain.

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Answer 2

It is explained in MSDN : Using Delegates (C# Programming Guide)