Object-oriented-class library, delegate, is and as operator, generic collection

Class Library:

is actually a bunch of class files, just do not see the source code of these classes, confidentiality is good.

Advantages: Good confidentiality

Cons: If this method is not good, the user cannot change it by themselves.

Most of them are DLL files. To use: Refer to Right-click, add Reference, browse, select to the appropriate DLL file, OK. Then add the "using namespace name" at the beginning

Commissioned:

A delegate can be understood as a pointer to a function.

Key words: Delegate

Declaration: public delegate int Firstdel (int a, int b);

To create a delegate variable:
Firstdel name = The same method as this delegate type;

In the class program, declare:

public delegate int Firstdel (int a, int b);

In the main function:

            Jiajian JJ = new Jiajian ();            Firstdel del = JJ. Jia;            Console.WriteLine (Del (10,20));    

IS and as operators:

is: Determine whether an object is a type

object is type name

Is this type returns TRUE, not this type returns false

As: Converts an object to a type, and if the conversion is unsuccessful, it assigns a null to the object without error.

Generic collection list<t>

Combines the benefits of collections and arrays

A set of fixed data types, not fixed lengths

Use:

Add at the beginning:

Using system.collections;using System.Collections.Generic;

In the main function:

            list<string> slist = new list<string> ();            Slist. ADD ("AAA");            Slist. ADD ("BBB");            String a = Slist[0];            list<int> ilist = new list<int> ();            IList. ADD (1);            IList. ADD (2);            list<jiajian> jlist = new list<jiajian> ();    

Universal variables:

Var

Dynamic

            var bb = "AAA";            var cc = new Random ();            var dd = new list<jiajian> ();            Dynamic EE = "AAA";            Dynamic FF = new Random ();            Dynamic GG = new list<random> ();   

Object-oriented-class library, delegate, is and as operator, generic collection