Polimorfizm, undan foydalanish mexanizmlari

rParent.getName () ga murojaat qilish A::getName() ga murojaat qilishga olib keladi. Biroq, A::getName() virtual funksiya bo’lganligi sababli, kompilyator A va C o’rtasida ”eng katta” avlodning metodini qidiradi. Bu holda, u C::getName ().
E’tibor bering, kompilyator D::getName() ga murojaat qilmaydi, chunki bizning asl ob’ektimiz D sinfi emas, C sinfi edi, shuning uchun faqat A va C sinflari orasidagi metodlar hisobga olinadi.
Dasturni bajarish natijasi:
rParent - bu C
Misol. Yanada murakkabroq misolni ko’ramiz. Oldingi qo’llanmadagi Animal sinfini ko’rib chiqamiz va ba’zi test kodlarini qo’shamiz:
#include
#include using namespace std; class Animal
{
protected:
string m_name;
Animal(string name)
{
m_name = name;
}
public:
string getName() { return m_name; } const char* speak() { return ” ???”; }
};
class Cat: public Animal
{
public:
Cat(string name)
: Animal(name)
{
}
const char* speakQ { return "Meow"; }
class Dog: public Animal
{
public:
Dog(string name)
: Animal(name)
{
}
const char* speakQ { return "Woof’; }
void report(Animal &animal)
{
cout << animal.getName() << animal.speak() <<” deydi”<< '\n';
}
int main()
{
Cat cat(”Matros”);
Dog dog(”Barsik”);
report(cat);
report(dog);
}
Dasturni bajarish natijasi:
Matros ??? deydi Barsik ??? deydi
Keling, xuddi shu sinfni speak() metodini virtual qilish orqali ko’rib chiqaylik:
#include
#include using namespace std; class Animal
{
protected:
string m_name;
Animal(string name)
{
m_name = name;
}
public:
string getName() { return m_name; } virtual const char* speak() { return "???"; }
};
class Cat: public Animal {
public:
Cat(string name)
: Animal(name)
{
}
virtual const char* speak() { return "Meow”; }
};
class Dog: public Animal {
public:
Dog(string name)
: Animal(name)
{
}
virtual const char* speak() { return "Woof"; }
void report( Animal &animal)
{
cout« animal.getName() « ""
}
int main()
{
Cat cat(MMatrosM);
Dog dog(MBarsikM);
report(cat);
report(dog);
}
Dastumi bajarish natijasi:
Matros Miyav deydi Barsik Vuf deydi
Bu ishladi!