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

POLIMORF OB'EKT-TELEFON YARATISH
Bir qo’ng’iroqdan ikkinchisiga telefon o’z shaklini o’zgartirishi lozim bo’lsin. Polimorf ob'ekt yaratish uchun avval virtual suzi yordamida virtual usullar yaratiladi:

class phone

{

public:

virtual void dial(char •number) { cout << "Nabor nomera " << number << endl; }

void answer(void) { cout << "Ojidanie otveta" << endl; }

void hangup(void) { cout << "Zvonok vihpolnen - povesit' trubku" << endl; }

void ring(void) { cout << "Zvonok, zvonok, zvonok" << endl; }

phone(char *number) { strcpy(phone::number, number); };

protected:

char number[13];

};

So’ngra dasturda asosiy sinf ob'ektiga ko’rsatkich yaratasiz.

phone *poly_phone;

Shaklni o’zgartirish uchun bu ko’rsatkiyach qiymatiniga hosilaviy sinf ob'ekti adresiga teng qilinadi:

poly_phone = (phone *) &home_phone;

Bu misolda (phone *), tiplarni keltirish operatoridir.

Qo’yidagi POLYMORP.CPP dasturda shu usuldan foydalanilgandir:

#include

#include

class phone

{

public:

virtual void dial(char *number) { cout << "Nabor nomera " << number << endl; }

void answer(void) { cout << "Ojidanie otveta" << endl; }

void hangup(void) { cout << "Zvonok vihpolnen - povesit' trubku" << endl; }

void ring(void) { cout << "Zvonok, zvonok, zvonok" << endl; }

phone(char *number) { strcpy(phone::number, number); };

protected:

char number[13] ;

};

class touch_tone : phone

{

public:

void dial(char * number) { cout << "Pik pik Nabor nomera " << number << endl; }

touch_tone(char *number) : phone(number) { }

};

class pay_phone: phone

{

public:

void dial(char *number) { cout << "Pojaluysta, oplatite " << amount << " tsentov" << endl; cout << "Nabor nomera " << number << endl; }

pay_phone(char *number, int amount) : phone(number) { pay_phone::amount = amount; }

private:

int amount;

};

void main(void)

{

pay_phone city_phone("702-555-1212", 25);

touch_tone home_phone("555-1212");

phone rotary("201-555-1212") ;

// Sdelat' ob'ekt diskovihm telefonom

phone *poly_phone = &rotary;

poly_phone->dial("818-555-1212");

// Zamenit' formu ob'ekta na knopochnihy telefon

poly_phone = (phone *) &home_phone;

poly_phone->dial("303-555-1212");

// Zamenit' formu ob'ekta na platnihy telefon

poly_phone = (phone *) &city_phone;

poly_phone->dial("212-555-1212");

}

Dastur bajarilishi natijasida ekranga kuyidagi ma'lumotlar hosil buladi:

S:\> POLYMORP

Nabor nomera 818-555-1212

Pik pik Nabor nomera 303-555-1212

Pojaluysta, oplatite 25 tsentov

Nabor nomera 212-555-1212