2、说明
考虑C++中的一个类"Person"。
//Person.h
class Person
{
private:
char* pFirstName;
char* pLastName;
public:
Person(const char* pFirstName, const char* pLastName); //constructor
~Person(); //destructor
void displayInfo();
void writeToFile(const char* pFileName);
};
创建完对象之后，我们能够访问它的数据成员和函数。
Person* pPersonObj = new_Person("Anjali", "Jaiswal");
//displaying person info
pPersonObj->Display(pPersonObj);
//writing person info in the persondata.txt file
pPersonObj->WriteToFile(pPersonObj, "persondata.txt");
//delete the person object
pPersonObj->Delete(pPersonObj);
pPersonObj = NULL;
3、在C中类的表现
继承-Employee类继承自Person类：
3.2、在C中结构体中的等效表示
如图所示，我们在基类结构体中声明了一个指针保存派生类对像，并在派生类结构体中声明一个指针保存基类对象。
创建Person对象
//Person.h
typedef struct _Person Person;
//pointers to function
typedef void (*fptrDisplayInfo)(Person*);
typedef void (*fptrWriteToFile)(Person*, const char*);
typedef void (*fptrDelete)(Person*) ;
typedef struct _person
{
void* pDerivedObj;
char* pFirstName;
char* pLastName;
fptrDisplayInfo Display;
fptrWriteToFile WriteToFile;
fptrDelete Delete;
}person;
Person* new_Person(const char* const pFristName,
const char* const pLastName); //constructor
void delete_Person(Person* const pPersonObj); //destructor
void Person_DisplayInfo(Person* const pPersonObj);
void Person_WriteToFile(Person* const pPersonObj, const char* const pFileName);
//Person.c
//construction of Person object
Person* new_Person(const char* const pFirstName, const char* const pLastName)
{
Person* pObj = NULL;
//allocating memory
pObj = (Person*)malloc(sizeof(Person));
if (pObj == NULL)
{
return NULL;
}
//pointing to itself as we are creating base class object
pObj->pDerivedObj = pObj;
pObj->pFirstName = malloc(sizeof(char)*(strlen(pFirstName)+1));
if (pObj->pFirstName == NULL)
{
return NULL;
}
strcpy(pObj->pFirstName, pFirstName);
pObj->pLastName = malloc(sizeof(char)*(strlen(pLastName)+1));
if (pObj->pLastName == NULL)
{
return NULL;
}
strcpy(pObj->pLastName, pLastName);
//Initializing interface for access to functions
//destructor pointing to destrutor of itself
pObj->Delete = delete_Person;
pObj->Display = Person_DisplayInfo;
pObj->WriteToFile = Person_WriteToFile;
return pObj;
}
Employee对象的结构
结论
