Why are use the delegates in C# and how to pass a parameter in delegate, also define the benefits.

Question

Ravi Vishwakarma · Accepted Answer

The C# delegates are like the function pointer present in C, C++, as you must have read pointers in C, C++ Normally the job of pointers is to hold the reference. The C# delegate is like a reference type variable that holds the reference to a method. And this reference can change at runtime. All delegates derive from System. Delegate Class. If you want to use delegate then you have to use the delegate keyword.
Syntax 
access-modifier delegate return type delegate-name(parameters) 
Exampleand 
using System;public class Program
{
and //declare delegate
and public delegate void DelegateFunction(int a, int b);
and public void Sum(int a, int b){
and Console.WriteLine('Sum : '+ (a+b));
and }
and public void Sub(int a, int b){
and Console.WriteLine('Substraction : '+ (a-b));
and }
and public void Mulifly(int a, int b){
and Console.WriteLine('Mulification : '+ (a*b));
and }
and public static void Main()
and {
and Program pr=new Program();
and //adding sum function in delegate
and DelegateFunction delfun=pr.Sum;
and delfun(45,12);
and //adding sub function in delegate
and delfun=pr.Sub;
and delfun(45,12);
and //adding Mulifly function in delegate
and delfun=pr.Mulifly;
and delfun(45,12);and }
}
Output
Sum : 57
Substraction : 33
Mulification : 540
Delegates are also called type-safe function pointers because the return type of the function is the same as the return type delegate.
We can also pass the delegate as a parameter, A method can also have a parameter of the delegate type.
access-modifier return-type fuction-name(delegate-name delegate-reference, arguments1, arguments2, … ){and delegate-reference(arguments1, arguments2, …)} 
Example
using System;public class Program
{
and //declare delegate
and public delegate void DelegateFunction(int a, int b);
and public void Sum(int a, int b){
and Console.WriteLine('Sum : '+ (a+b));
and }
and public void Sub(int a, int b){
and Console.WriteLine('Substraction : '+ (a-b));
and }
and public void Mulifly(int a, int b){
and Console.WriteLine('Mulification : '+ (a*b));
and }
and // delegate as parameter
and public void DelegateAsParameter(DelegateFunction delegatefunction, int a, int b)
and {
and delegatefunction(a,b);
and }
and public static void Main()
and {
and Program pr=new Program();
and pr.DelegateAsParameter(pr.Sum,45,12);		
and pr.DelegateAsParameter(pr.Sub,45,12);
and pr.DelegateAsParameter(pr.Mulifly,45,12);
and }
}
Output
Sum : 57
Substraction : 33
Mulification : 540
Multicast Delegates 
A delegate can point to more than one method, this means that a delegate can keep the address of more than one method and call them one by one. That is, a delegate that points to multiple methods is called a multicast delegate.
Example
using System;public class Program
{
and //declare delegate
and public delegate void DelegateFunction(int a, int b);
and public void Sum(int a, int b){
and Console.WriteLine('Sum : '+ (a+b));
and }
and public void Sub(int a, int b){
and Console.WriteLine('Substraction : '+ (a-b));
and }
and public void Mulifly(int a, int b){
and Console.WriteLine('Mulification : '+ (a*b));
and }
and // delegate as parameter
and public void DelegateAsParameter(DelegateFunction delegatefunction, int a, int b)
and {
and delegatefunction(a,b);
and }
and public static void Main()
and {
and Program pr=new Program();
and // Multicast Delegates adding one by function in one delegate
and DelegateFunction dfun=pr.Sum;
and dfun+=pr.Sub;
and dfun+=pr.Mulifly;
and // calling the delegate
and dfun(45,12);
and }
}
Output
Sum : 57
Substraction : 33
Mulification : 540

Why are use the delegates in C# and how to pass a parameter in delegate, also define the benefits.

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