Delegate delegate in C #

Delegates are also called delegates , representing a class of methods. This class of methods has the same modifiers, formal parameters, and return value types .

1. The delegate is both a method and a delegate is declared as follows: Add the delegate [' d?l?ɡ?t] keyword after the modifier

1  Public Delegate void Del (string message);

From the format, it is very similar to the declaration of the method, that is, more than a delegate keyword. It represents a method that declares a class that has a modifier of public, a string-type parameter, and no return value.

2. But the delegate is not an ordinary method, because it is also a class, so the delegate can only be declared, but not defined, such as cannot write:

private delegate void Doing( string name){        System.Windows.MessageBox.Show(); }

3. Instantiating a delegate, invoking a delegate

1 //declares a void, and the parameter is a delegate of string2  Public Delegate voidDel (stringname);3  4 //define a cut method5  Public voidCutstringname)6 {7System.Windows.MessageBox.Show ("Fuck"+name);8 }9 //instantiate the delegate, pass the parameter is a method of the name, here is the cutTenDel A =NewDel (cut); OneA"CCC");//call the delegate, which is equivalent to calling cut ("CCC");

4. What is the use of the Commission and what does it mean to be so complicated?

The method name is passed as a method parameter, which improves the variability and flexibility of the code; The delegate is used primarily for events and callback functions.

5. Delegated multicast (multicasting of a Delegate) operation "+ =", "-="

1 usingSystem;2  3 Delegate intNumberchanger (intn);4 namespaceDELEGATEAPPL5 {6    classtestdelegate7    {8       Static intnum =Ten;9        Public Static intAddnum (intp)Ten       { Onenum + =p; A          returnnum; -       } -   the        Public Static intMultnum (intq) -       { -Num *=Q; -          returnnum; +       } -        Public Static intGetnum () +       { A          returnnum; at       } -   -       Static voidMain (string[] args) -       { -          //Create a delegate instance - Numberchanger NC; inNumberchanger NC1 =NewNumberchanger (addnum); -Numberchanger NC2 =NewNumberchanger (multnum); toNC =nc1; +NC + = NC2;//here, the NC actually binds 2 delegates, which are executed in the order in which they are bound . -          //Call Multicast thenc5); *Console.WriteLine ("Value of Num: {0}", Getnum ()); $ Console.readkey ();Panax Notoginseng       } -    } the}

Note : Delegate objects can be merged using the "+ =" operator. A merge delegate invokes the two delegates it merges. Only delegates of the same type can be merged.

The "-=" operator can be used to remove a component delegate from a merged delegate.

No matter how far you go, looking back is also necessary. ********************************************************

Delegate delegate in C #