练习50

#include <iostream>
using namespace std;
class Mammal {
public:
Mammal() {
cout << "Mammal constructor...\n";
}
virtual ~Mammal() {
cout << "Mammal destructor...\n";
}
virtual void speak() const {
cout << "Mammal speak!\n";
}
};


class Dog: public Mammal {
public:
Dog() {
cout << "Dog Constructor...\n";
}
~Dog() {
cout << "Dog destructor...\n";
}
void speak() const {
cout << "Woof!\n";
}
};


int main() {
Mammal *pDog = new Dog;
pDog->speak();
delete pDog;
return 0;
}