20141214--c# Parent class, subclass

Primary:

Subclass contains all property methods of the parent class
All subclasses can be converted directly to the parent class type
When a parent class type variable contains an object of a subclass, it can be converted to that subclass type.

The parent class and the child class are loaded:

New= (Ren) m; // Man subclass converted to Ren parent class New  = (man) r; // when converted to a parent class and then converted to a subclass, it can only be converted to the original subclass, and cannot be converted to another child class

You need to use forced reload.

Private and protected:

Private can only be used as a member variable in the current class.

Protected can only be used as member variables in the current class or in subclasses.

When the subclass is initialized, the parent class is initialized first, and the constructor in the parent class is executed.

Write in the parent class:

  private  int  hello;// private can only be used as a member variable in its own class  protected
     int  world; //        protected can only be used as a member variable in its own class and subclass  public  Ren () //  constructor (first executed)   {world  + = 10  ;       Hello  = 0  ;  public  void   Ren1 () {Console.WriteLine (World); }

In a sub-class:

class Man:ren// plus ": ren" subclass, indicating that man is a subclass of Ren.      {         public  Mans ()        {            5///  You can use protected variables in subclasses. You cannot use the private variable.          }        publicvoid  man1 ()        {            Console.WriteLine (World) ;        }    }

In another sub-class:

 class Women:ren// plus the ": Ren" subclass, which indicates that women is a subclass of Ren.      {        public  Women ()        {            7;        }          Public void women1 ()        {            Console.WriteLine (world);        }    }

Main function

Static voidMain (string[] args) {//subclass contains all property methods of the parent class//all subclasses can be converted directly to the parent class type//when a parent class type variable contains an object of a subclass, it can be converted to that subclass type. Ren rr =NewRen (); Rr.ren1 ();//The print result is tenMans M=NewMan (); M.man1 ();//the printed result isWomen W=Newwomen (); W.women1 ();//The print result isConsole.ReadLine (); }

When static is added to the parent class

Private intHello//private can only be used as member variables in your own class       protected Static intWorld//protected can only be used as member variables in their own classes and subclasses//note here that a static static variable (protected) has been added, unlike above        PublicRen ()//Constructors (performed first){ World+=Ten; Hello=0; }       Public voidRen1 () {Console.WriteLine (World); }

Output Result:

            New Ren ();            Rr.ren1 (); // The print result is ten Man             m=new man ();            M.man1 (); // The print result is New Women ();                          W.women1 (); // printing results are

Its principle:

The protected variable will not change every time the initialization (new) is initialized.

10+15=25; (the first 10 is a change in the initialization of Ren)

25+17=42; (25 is the change when the man is initialized)

Method calls to the parent class and child classes:

When a subclass has a method with the same name in its parent class, the new is the one whose method is called.

Parent class:

 Public void Shuohua ()        {            Console.WriteLine (" speak:");        }

Man sub-category:

 Public void Shuohua ()        {            Console.WriteLine (" English ");        }

Note Two is a method with the same name.

In the main function:

           M.shuohua (); //Call the    method in man Print Result: English            Rr.shuohua (); //Call is in the Ren method    Printing Results: Speaking:              = (Ren) m; // The man class M is coerced into the Ren class.             Rr.shuohua ();  the method that is called in Ren   prints the result: Speak:            = (man) RR;   cast The Ren class RR into the man class.             M.shuohua ();   Call the method in man   print Result: English 

20141214--c# Parent class, subclass