What are Delegates and what are the uses of the Delegates

A delegate in C# is similar to a function pointer in C or C++. Using a delegate allows the developer to encapsulate a reference to a method inside a delegate object.

Delegates are basically used in these situations:

  • These are used to represent or refer to one or more functions.
  • These can only be used to define call-back methods.
  • In order to consume a delegate, we need to create an object to delegate.

Syntax of delegates is :

[modifier] delegate [returntype] [delegatename] ([parameterlist]);

modifier: It is the required modifier which defines the access of delegate and it is optional to use.

delegateIt is the keyword which is used to define the delegate.

returntypeIt is the type of value returned by the methods which the delegate will be going to call. It can be void. A method must have the same return type as the delegate.

delegatename: It is the user-defined name or identifier for the delegate.

parameterlist: This contains the parameters which are required by the method when called through the delegate.

Example of simple delegate:

class Program {  
        static void DisplayName(string S) {  
            Console.WriteLine("My Name is :" + S);  
        }  
        delegate void func(string a);  
        static void Main(string[] args) {  
            func object= new func(DisplayName);  
            object("Code Hunger");  
            Console.Read();  
        }  
    }  

There are two types of delegates:

  • Single Cast Delegate
  • Multi Cast Delegate

Single Cast Delegate

A delegate that represents only a single function is known as Single Cast Delegate.

Multi Cast Delegate

A delegate that represents more than one function is known as Multi Cast Delegate.

Example of multicast delegates:

 class Program {  
        public void Addition(int a, int b) {  
            Console.WriteLine("Sum is:" + (a + b));  
        }  
        public void Subtraction(int a, int b) {  
            Console.WriteLine("Difference is:" + (a - b));  
        }  
        public void Multiplication(int a, int b) {  
            Console.WriteLine("Product is:" + (a * b));  
        }  
        public void Division(int a, int b) {  
            Console.WriteLine("Quotient is:" + (a / b));  
        }  
    }  
    public delegate void MultiCastDelegate(int a, int b);  
    class ExampleDelegate {  
        static void Main() {  
            Program object = new Program();  
            MultiCastDelegate obj= new MultiCastDelegate(object.Multiply);  
            obj += object.Add;  
            obj += object.Substract;  
            obj += object.Divide;  
            obj(40, 10);  
            obj -= object.Add;  
            obj -= object.Divide;  
            obj(50, 10);  
            Console.ReadLine();  
        }  
    }  
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