C的继承和多态

<参考自 http://www.cnblogs.com/skynet/archive/2010/09/23/1833217.html>

 

person.h

 1 // Base class
 2 
 3 #pragma once
 4 
 5 typedef struct _Person Person;
 6 
 7 typedef void (*fptrDisplayInfo)(const Person *);
 8 typedef void (*fptrWritetoFile)(const Person *, const char *);
 9 typedef void (*fptrDelete)(Person *);
10 
11 typedef struct _Person {
12     char * pFName;
13     char * pLName;
14     void * pDerivedObj; // Derived Object
15 
16     fptrDisplayInfo Display; // public interface, private not need to be defined
17     fptrWritetoFile WriteToFile;
18     fptrDelete Delete;
19 }Person;
20 
21 Person * new_person(const char *pFName, const char *pLName);
22 void delete_person(Person * obj);
23 void Person_DisplayInfo(const Person * obj);
24 void Person_WriteToFile(const Person * obj, const char * pFile);

person.c

 1 #include "person.h"
 2 #include <stdlib.h>
 3 #include <string.h>
 4 #include <stdio.h>
 5 
 6 Person * new_person(const char *pFirstName, const char *pLastName) {
 7     Person * pObj = (Person *)malloc(sizeof(Person));
 8     if (pObj == NULL)
 9         return NULL;
10 
11     pObj->pFName = (char *)malloc(strlen(pFirstName)+1);
12     if (pObj->pFName == NULL)
13         return NULL;
14     strcpy(pObj->pFName, pFirstName);
15 
16     pObj->pLName = (char *)malloc(strlen(pLastName)+1);
17     if (pObj->pLName == NULL)
18         return NULL;
19     strcpy(pObj->pLName, pLastName);
20 
21     pObj->Display = Person_DisplayInfo;
22     pObj->WriteToFile = Person_WriteToFile;
23     pObj->Delete = delete_person;
24     pObj->pDerivedObj = pObj;
25 
26     return pObj;
27 }
28 
29 void delete_person(Person * obj) {
30     if (obj == NULL)
31         return;
32     free(obj->pFName); // Caution
33     free(obj->pLName); // Caution
34     free(obj);
35 }
36 
37 void Person_DisplayInfo(const Person * obj) {
38     printf("First Name: %s, Last Name: %s", obj->pFName, obj->pLName);
39 }
40 
41 void Person_WriteToFile(const Person * obj, const char * pFile) {
42     FILE * fp = fopen(pFile, "wb");
43     if (fp == NULL)
44         return;
45     char name[100];
46     sprintf(name, "First Name: %s, Last Name: %s\n", obj->pFName, obj->pLName);
47     fwrite(name, strlen(name)+1, 1, fp);
48 }

emploee.h

 1 // Implement class
 2 
 3 #pragma once
 4 
 5 #include "person.h"
 6 
 7 typedef struct _Emploee Emploee;
 8 
 9 // here add new function pointer
10 
11 typedef struct _Emploee {
12     char * company;
13     char * department;
14     int salary;
15 }Emploee;
16 
17 Person * new_emploee(const char * pFirstName, const char * pLastName, 
18                 const char * pCompany, const char * department, int salary);
19 void delete_emploee(Person * obj);
20 void Emploee_DisplayInfo(const Person * obj);
21 void Emploee_WriteToFile(const Person * obj, const char * pFile);

emploee.c

 1 #include "emploee.h"
 2 #include <stdlib.h>
 3 #include <string.h>
 4 
 5 Person * new_emploee(const char * pFirstName, const char * pLastName, 
 6     const char * pCompany, const char * pDepartment, int salary) {
 7         Person * pObj = new_person(pFirstName, pLastName);
 8         if (pObj == NULL)
 9             return NULL;
10 
11         Emploee  * emploee = (Emploee *)malloc(sizeof(Emploee));
12         if (emploee == NULL) {
13             delete_person(pObj);
14             return NULL;
15         }
16         pObj->pDerivedObj = emploee;
17 
18         emploee->company = (char *)malloc(sizeof(strlen(pCompany)+1));
19         if (emploee->company == NULL) {
20             delete_person(pObj);
21             return NULL;
22         }
23 
24         emploee->department = (char *)malloc(sizeof(strlen(pDepartment)+1));
25         if (emploee->department == NULL) {
26             delete_person(pObj);
27             delete [] emploee->company;
28             return NULL;
29         }
30 
31         emploee->salary = salary;
32         
33         pObj->Delete = delete_emploee;
34         pObj->Display = Emploee_DisplayInfo;
35         pObj->WriteToFile = Emploee_WriteToFile;
36 
37         return pObj;
38 }
39 
40 void delete_emploee(Person * obj) {
41     if (obj == NULL)
42         return;
43     Emploee * pEmploee = (Emploee*)obj->pDerivedObj;
44     free(pEmploee->company);
45     free(pEmploee->department);
46     free(pEmploee);
47     delete_person(obj);
48 }
49 
50 void Emploee_DisplayInfo(const Person * obj) {
51 
52 }
53 
54 void Emploee_WriteToFile(const Person * obj, const char * pFile) {
55 
56 }

main.c

 1 #define _CRTDBG_MAP_ALLOC
 2 #include <crtdbg.h>
 3 #include "person.h"
 4 #include "emploee.h"
 5 
 6 #define NULL 0
 7 
 8 int main()
 9 {
10     Person * person = new_person("Micheal", "Jackson");
11     Person * emploee = new_emploee("Kobe", "Bryant", "Lakes", "Player", 2000);
12 
13     person->Display(person);
14     person->WriteToFile(person, "123.txt");
15     person->Delete(person);
16     person = NULL;
17 
18     emploee->Display(emploee);
19     emploee->WriteToFile(emploee, "456.txt");
20     emploee->Delete(emploee);
21     _CrtDumpMemoryLeaks();
22     return 0;
23 }

 

转载于:https://www.cnblogs.com/aoun/p/3728307.html