순허함수와 추상류의 계승과 실현

코드를 직접 보면 주석이 매우 상세하다
먼저 헤더 파일 "virtual function.h"를 씁니다.

   1: #ifndef _VIRTUAL_FUNCTION_H_

   2: #define _VIRTUAL_FUNCTION_H_

   3:  

   4: #include <iostream>

   5: #define   Human

   6: #define   Female

   7: #define    Women

   8: #define    Girl

   9: class  

  10: {    

  11:     int age;    //    ，  

  12: public:

  13:      ()

  14:     {

  15:         std::cout << "      " << std::endl;

  16:         age = 18; 

  17:     }

  18:     ~ ()

  19:     {

  20:         std::cout << "       " << std::endl;

  21:     }

  22:     //       ，    ，    

  23:     virtual void showAge() = 0;

  24: };

  25: class  

  26: {

  27: public:

  28:     //             

  29:      ()

  30:     {    //               

  31:         std::cout << "      " << std::endl;

  32:     }

  33:     ~ ()

  34:     {    //               

  35:         std::cout << "      " << std::endl;

  36:     }

  37:     //    ，    ，    

  38:     virtual void showMaxim() = 0

  39:     {

  40:         std::cout << "     。。。" << std::endl;

  41:     }

  42: };

  43:  

  44: class    :public  , public  

  45: {

  46:     //    ，     ，    

  47:     int charm;    //        

  48: public:

  49:     //      

  50:       ()

  51:     {

  52:         std::cout << "       。。。" << std::endl;

  53:     }

  54:     ~  ()

  55:     {

  56:         std::cout << "       " << std::endl;

  57:     }

  58:     //             ，        

  59:     virtual void showAge()

  60:     {

  61:         std::cout << "    20  " << std::endl;

  62:     }

  63:     virtual void showMaxim()

  64:     {

  65:         std::cout << "        " << std::endl;

  66:     }

  67: };

  68:  

  69: class    :public   

  70: {

  71: public:

  72:     void showAge()

  73:     {

  74:         std::cout << "        ，    "<<std::endl;

  75:     }

  76:     void showMaxim()

  77:     {

  78:         std::cout << "        ，     "<<std::endl;

  79:     }

  80: };

  81:  

  82: #endif // !_VIRTUAL_FUNCTION_H_

메일 하나 더 주세요.cpp

   1: #include "virtual_function.h"

   2:  

   3: int main()

   4: {

   5:     {

   6:            *pgirl = new   ;

   7:           *phuman = pgirl;

   8:           *pfemale = pgirl;

   9:            *pwomen = pgirl;

  10:  

  11:         //                    

  12:         std::cout << "
======                    ============" << std::endl;

  13:         pgirl->showAge();

  14:         pgirl->showMaxim();

  15:         //phuman    showAge

  16:         phuman->showAge();

  17:         //pfemale    showMaxin

  18:         pfemale->showMaxim();

  19:         //       

  20:         pwomen->showAge();

  21:         pwomen->showMaxim();

  22:  

  23:         //                    

  24:         std::cout << "
======                    ============" << std::endl;

  25:         pgirl->  ::showAge();

  26:         pgirl->  ::showMaxim();

  27:         //phuman    ，           

  28:         //phuman->  ::showAge();

  29:         //pfemale    ，       

  30:         //pfemale->  ::showMaxim();

  31:         //       

  32:         pwomen->  ::showAge();

  33:         pwomen->  ::showMaxim();

  34:  

  35:         //                ，       showAge  ，    

  36:         //       ，           

  37:         std::cout << "
======                   ============" << std::endl;

  38:     //    pgirl-> ::showAge();    //    ，    

  39:         pgirl-> ::showMaxim();

  40:         //phuman    showAge

  41:     //    phuman-> ::showAge();

  42:         //pfemale    showMaxin

  43:         pfemale-> ::showMaxim();

  44:         //       

  45:     //    pwomen-> ::showAge();

  46:         pwomen-> ::showMaxim();

  47:  

  48:  

  49:  

  50:         std::cout << "

======      sizeof  ,     ============" << std::endl;

  51:         // 32    

  52:         std::cout << "sizeof (  )=" << sizeof(  ) << std::endl;    //16         showAge showMaxim   ，        

  53:         std::cout << "sizeof (  )=" << sizeof(  ) << std::endl;    //16              ，       4   

  54:         std::cout << "sizeof (   )=" << sizeof( ) << std::endl;    //8        age 4   ，      (vfptr)     

  55:         std::cout << "sizeof (   )=" << sizeof( ) << std::endl;    //4              ， vfptr     

  56:  

  57:         std::cout << "pgirl=\t\t" << pgirl << std::endl;        //    01A92B8

  58:         std::cout << "pwomen=\t\t" << pwomen << std::endl;    //    01A92B8

  59:         std::cout << "phuman=\t\t" << phuman << std::endl;    //    01A92B8

  60:         std::cout << "pfemale=\t" << pfemale << std::endl;    //    01A92C0

  61:  

  62:  

  63:     }

  64:  

  65:     std::cin.get();

  66:     return 0;

  67: }

출력 결과는 다음과 같습니다.

       。。。

======                    ============

        ，    

        ，     

        ，    

        ，     

        ，    

        ，     

======                    ============

    20  

    20  

======                   ============

     。。。

     。。。

     。。。

======      sizeof  ,     ============

sizeof (  )=16

sizeof (  )=16

sizeof (   )=8

sizeof (   )=4

pgirl=        00586D38

pwomen=        00586D38

phuman=        00586D38

pfemale=    00586D40