why we need delgate in C#

siddangoud

but it is difficult to me understand.please give some simple scenario so why we need it

if not used delegate what will be the problem....

A delegate is a type that represents references to methods with a particular parameter list and return type. When you instantiate a delegate, you can associate its instance with any method with a compatible signature and return type. You can invoke (or call) the method through the delegate instance.

The main benefit of delegate is that you can assign or pass methods/properties as a parameter. Delegate can be understood as a kind of interfaces, and specific methods to achieve this interface, only need to be concerned at the development stage can call the delegate definition, regardless of how or where it achieved.

It's useful in GUI programming because your whole program could be waiting for the user to do something and you have no way of knowing what they will do first. Using delegates allows the functionality of your program to be connected to the UI in such a way that the user can do things in any way they want.

You could refer to the following articles, they provide us some detailed explanation.

6 important uses of Delegates and Events

C# - Delegates 101 - A Practical Example:

Best Regards,

Yong Lu

.NET forums are moving to a new home on Microsoft Q&A, we encourage you to go to Microsoft Q&A for .NET for posting new questions and get involved today.

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siddangoud

Member

5 Points

53 Posts

Re: why we need delgate in C#

May 09, 2018 03:10 AM|siddangoud|LINK

Hi

thanks for reply...

below code u can ref

using System;

delegate int NumberChanger(int n);
namespace DelegateAppl {
   
   class TestDelegate {
      static int num = 10;
      
      public static int AddNum(int p) {
         num += p;
         return num;
      }
      public static int MultNum(int q) {
         num *= q;
         return num;
      }
      public static int getNum() {
         return num;
      }
      static void Main(string[] args) {
         //create delegate instances
         NumberChanger nc1 = new NumberChanger(AddNum);
         NumberChanger nc2 = new NumberChanger(MultNum);
         
         //calling the methods using the delegate objects
         nc1(25);
         Console.WriteLine("Value of Num: {0}", getNum());
         nc2(5);
         Console.WriteLine("Value of Num: {0}", getNum());
         Console.ReadKey();
      }
   }
}

 below are some point 

ref

Delegates can be chained together; for example, multiple methods can be called on a single event. how is it


in this example what is advantage of using delegate.

they told  like 
 The reference can be changed at runtime. but i am confusing on it

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Yohann Lu

Star

11464 Points

2439 Posts

Re: why we need delgate in C#

May 10, 2018 02:52 AM|Yohann Lu|LINK

Hi siddangoud,

siddangoud
Delegates can be chained together; for example, multiple methods can be called on a single event. how is it

You can refer the following sample.

  class Program
    {
        delegate int NumberChanger(int n);

        static int num = 10;

        public static int AddNum(int p)
        {
            num += p;
            return num;
        }
        public static int MultNum(int q)
        {
            num *= q;
            return num;
        }


        static void Main(string[] args)
        {
            //create delegate instances
            NumberChanger nc1;
            nc1 = AddNum;
            nc1 += MultNum;

            Console.WriteLine(nc1(25).ToString()); //calls boths AddNum and MultNum
            Console.ReadKey();

        }
    }

How to: Combine Delegates (Multicast Delegates)(C# Programming Guide):
https://docs.microsoft.com/en-us/dotnet/csharp/programming-guide/delegates/how-to-combine-delegates-multicast-delegates

>>The reference can be changed at runtime. but i am confusing on it

siddangoud
The reference can be changed at runtime. but i am confusing on it

May be multiple objects can be assigned/remove to one delegate instance by using the +/- operator.

You can start a new thread if you have a new question.

Best Regards,

Yong Lu

.NET forums are moving to a new home on Microsoft Q&A, we encourage you to go to Microsoft Q&A for .NET for posting new questions and get involved today.

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