Delegates SingleCast & MultiCast

 In C#, there are two kinds of Delegates. These are:

SingleCast Delegate: A single function or method is referred to as a delegate.

// Using of Delegates

using System;

class Geeks 

{

    // Declaring the delegates

    // Here return type and parameter type should 

    // be same as the return type and parameter type

    // of the two methods

    // "addnum" and "subnum" are two delegate names

    public delegate void addnum(int a, int b);

    public delegate void subnum(int a, int b);

    public void sum(int a, int b)

    {

        Console.WriteLine("(100 + 40) = {0}", a + b);

    }

    public void subtract(int a, int b)

    {

        Console.WriteLine("(100 - 60) = {0}", a - b);

    }

    // Main Method

    public static void Main(String []args)

    {

        // creating object "obj" of class "Geeks"

        Geeks obj = new Geeks();

        // creating object of delegate, name as "del_obj1" 

        // for method "sum" and "del_obj2" for method "subtract" &

        // pass the parameter as the two methods by class object "obj"

        // instantiating the delegates

        addnum del_obj1 = new addnum(obj.sum);

        subnum del_obj2 = new subnum(obj.subtract);

        // pass the values to the methods by delegate object

        del_obj1(100, 40);

        del_obj2(100, 60);

        // These can be written as using

        // "Invoke" method

        // del_obj1.Invoke(100, 40);

        // del_obj2.Invoke(100, 60);

    }

}

MultiCast Delegate: Delegate refers to the delegation of multiple functions or methods.

// C# program to illustrate the 

// Multicasting of Delegates

using System;

class rectangle {

// declaring delegate

public delegate void rectDelegate(double height,

                                  double width);

    // "area" method

    public void area(double height, double width)

    {

        Console.WriteLine("Area is: {0}", (width * height));

    }

    // "perimeter" method

    public void perimeter(double height, double width)

    {

        Console.WriteLine("Perimeter is: {0} ", 2 * (width + height));

    }

// Main Method

public static void Main(String []args)

{ 

    // creating object of class 

    // "rectangle", named as "rect"

    rectangle rect = new rectangle();

    // these two lines are normal calling

    // of that two methods

    // rect.area(6.3, 4.2);

    // rect.perimeter(6.3, 4.2);

    // creating delegate object, name as "rectdele"

    // and pass the method as parameter by 

    // class object "rect"

    rectDelegate rectdele = new rectDelegate(rect.area);

    

    // also can be written as 

    // rectDelegate rectdele = rect.area;

    // call 2nd method "perimeter"

    // Multicasting

    rectdele += rect.perimeter; 

    // pass the values in two method 

    // by using "Invoke" method

    rectdele.Invoke(6.3, 4.2);

    Console.WriteLine();

    

    // call the methods with 

    // different values

    rectdele.Invoke(16.3, 10.3);

}

}