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Basic Theory
Delegates are used to make callbacks and to do other tasks in C#. They are used to pass methods around. If you’re an experienced programmer, you will notice that delegates and function pointers of c/c++ are similar to each other. They are used to reference a method and can be derived implicitly using the “System.Delegate Class.” You can declare a delegate using the “delegate” keyword using the template below:
delegate < delegate name>()
**Creating our first Delegate:
**
public delegate void PointToVoidMethod(int a, int b);
This delegate encapsulates any method that takes two integers as parameters and return with a void.
Then we create two void methods to add two numbers and to find the square of two number.
public void addNumber(int a, int b)
{
Console. WriteLine($"The Value is {a+b}");
}
public void FindSquareOfNumber( int s, int p )
{
Console. WriteLine($"The square is {Math.Pow(s, p)}");
}
You can see that both methods have the same signature as the delegate (i.e. two integer parameters and a void return type), so it can be used with our delegate.
Now write the following code in your main method:
static int Main(string[] args)
{
FirstLessonDelegates frst = new FirstLessonDelegates();
PointToVoidMethof ptm = new PointToVoidMethof(frst.addNumber);
ptm(20, 30);
PointToVoidMethof fsq = frst.FindSquareOfNumber;
fsq(2, 5);
ReadKey();
return 0;
}
I created a new instance of the class with object name frst and a new instance of the delegate.
Now i have referenced both methods with the delegates with the PointToMethod delegate. As you can see, I initialized both methods differently which is okay. But, it is advisable to initialize the method using the second technique, because the first technique is outdated.
The Image above shows the result of the code