Polimorfizm va uning turlari. Virtual funksiya. Abstrakt sinf va funksiyalar. 12 Mavzu

Abstrakt sinf tushunchasi

• C++ tilida kamida bitta virtual funksiyaga ega bo’lgan sinf abstrakt sinf deyiladi.
• Abstrakt sinfning asosiy xususiyatidan biri shuki, ushbu turdagi sinfdan obyekt olib bo’lmaydi.
• Demak sinfni to’la abstractligini ta’minlash uchun quyidagi qonuniyatdan foydalanamiz:
• class base{
• public:
• virtual vfunc(args....) = 0;
• ..... }

Misol

• class Base{
• public:
• virtual void display( int i) =0; };
• class Derv: public Base{
• public:
• void display(int j) { cout<<"Derv::"<
• int main(){
• Base b; // xato, chunki Base sinf abstrakt
• Base *ptr = new Derv; ptr->display(10); }

Virtual base classlar

• Agar nasl olinayotgan class bir necha base classdan nasl olganda hatolik mavjud bo’ladi. Bunday holatlarda nima qilish kerak? Bunday holatlarda virtual base classlar ishlatiladi.

protected sin a’zolariga murojaat

• class base { public: int i; };
• class derived1 : public base { public: int j; };
• class derived2 : public base { public: int k; };
• class derived3 : public derived1, public derived2 {
• public: int sum;};
• int main(){
• derived3 ob; ob.i = 10;
• ob.j = 20; ob.k = 30;
• ob.sum = ob.i + ob.j + ob.k;}

• Bu kodda hatolik mavjud:

• Hatolik qaysi i???

Oldingi misolni hatoligini to’g’irlash

• class base { public: int i; };
• class derived1 : public base { public: int j; };
• class derived2 : public base { public: int k; };
• class derived3 : public derived1, public derived2 {
• public: int sum;};
• int main(){
• derived3 ob;
• ob.derived1::i = 10;
• ob.j = 20; ob.k = 30; }

• Bu kodda hatolik mavjud:

• :: orqali qaysi classnikini ishlatish aytildi