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);
}
}
