1 – dars. C++ Dasturlash tilining kelib chiqishi xaqida ma’lumot

Sodda vorislik

Vorislik hosilaviy sinfning mavjud asosiy sinfning harakteristikalarini merosga olish hususiyatidir. Misol uchun asosiy sinf employee mavjud bo’lsin:

class employee

{

public:

employee(char *, char *, float);

void show_employee(void);

private:

char name[64];

char position[64];

float salary;

};

Dasturda yangi manager sinfi yaratib employee sinfining qo’yidagi elementlarini merosga olishi lozim bo’lsin:

float annual_bonus;

char company_car[64];

int stock_options;

U holda manager sinfi qo’yidagicha ta'riflanadi:

class manager : public employee

{

public:

manager(char *, char *, char *, float, float, int);

void show_manager(void);

private:

float annual_bonus;

char company_car[64];

int stock_options;

};

Hosilaviy sinf asosiy sinfning elementlariga to’g’ridan – to’g’ri nuqta operatori orqali murojaat qila olmaydi. Qo’yidagi MGR_EMP.CPP dasturda vorislikdan foydalanish ko’rsatiladi:

#include

#include

class employee

{

public:

employee(char *, char *, float);

void show_employee(void);

private:

char name [ 64 ];

char position[64];

float salary;

};

employee::employee(char *name, char *position,float salary)

{

strcpy(employee::name, name);

strcpy(employee::position, position);

employee::salary = salary;

}

void employee::show_employee(void)

{

cout << "Imya: " << name << endl;

cout << "Doljnost': " << position << endl;

cout << "Oklad: $" << salary << endl;

}

class manager : public employee

{

public:

manager(char *, char *, char *, float, float, int);

void show_manager(void);

private:

float annual_bonus;

char company_car[64];

int stock_options;

};

manager::manager(char *name, char *position, char *company_car, float salary, float bonus, int stock_options) : employee(name, position, salary)

{

strcpy(manager::company_car, company_car) ;

manager::annual_bonus = bonus ;

manager::stock_options = stock_options;

}

void manager::show_manager(void)

{

show_employee();

cout << "Mashina firmih: " << company_car << endl;

cout << "Ejegodnaya premiya: $" << annual_bonus << endl;

cout << "Fondovihy optsion: " << stock_options << endl;

}

void main(void)

{

employee worker("Djon Doy", "Programmist", 35000);

manager boss("Djeyn Doy", "Vitse-prezident ", "Lexus", 50000.0, 5000, 1000);

worker.show_employee() ;

boss.show_manager();

}

Bu misolda manager sinfi konstruktoriga e'tibor berish lozimdir. Asosiy sinfning konstruktorini qo’yidagicha chaqirish lozimdir:

manager::manager(char *name, char *position, char *company_car, float salary, float bonus, int stock_options) :

employee(name, position, salary) //————————————— Konstruktor bazovogo klassa

{

strcpy(manager::company_car, company_car);

manager::annual_bonus = bonus;

manager::stock_options = stock_options;

}

Yana shunga e'tibor berinki show_manager funktsiyasi show_employee funktsiyasini chaqirishi mumkin, chunki manager sinfi employee sinfining vorisi bo’lgani uchun, umumiy elemenlariga murojaat qilishi mumkindir. Ikkinchi misol

Misol uchsun book asosiy sinfi mavjud:

class book

{

public:

book (char *, char *, int);

void show_book(void);

private:

char title[64];

char author[b 4];

int pages;

};

Yangi library_card sinfi book sinfiga qo’yidagi elemenlarni qo’shishi lozim:

char catalog[64];

int checked_out; // 1, agar tekshirilgan bulsa, aks holda O

Dasturda bu sinf vorislik yordamida qo’yidagicha ta'riflanishmi lozim

class library_card : public book

{

public:

library_card(char *, char *, int, char *, int);

void show_card(void);

private:

char catalog[64] ;

int checked_out;

};

Qo’yidagi BOOKCARD.CPP dasturida bu sinflardan foydalanish ko’rsatilgan:

#include

#include

class book

{

public:

book(char *, char *, int);

void show_book(void);

private:

char title [64];

char author[64];

int pages;

};

book::book(char •title, char *author, int pages)

{

strcpy(book::title, title);

strcpy(book::author, author);

book::pages = pages;

}

void book::show_book(void)

{

cout << "Nazvanie: " << title << endl;

cout << "Avtor: " << author << endl;

cout << "Stranits: " << pages << endl;

}

class library_card : public book

{

public:

library_card(char *, char *, int, char *, int);

void show_card(void) ;

private:

char catalog[64];

int checked_out;

};

library_card::library_card(char *title, char *author, int pages, char *catalog, int checked_out) : book(title, author, pages)

{

strcpy(library_card::catalog, catalog) ;

library_card::checked_out = checked_out;

}

void 1ibrary_card::show_card(void)

{

show_book() ;

cout << "Katalog: " << catalog << endl;

if (checked_out) cout << "Status: proverena" << endl;

else cout << "Status: svobodna" << endl;

}

void main(void)

{

library_card card( "Uchimsya programmirovat' na yazihke C++", "Jamsa", 272, "101SRR", 1);

card.show_card();

}
Yana shunga e'tibor berinki library_card konstruktori book sinfi konstruktorini chaqiradi.