C++中多态性实现的问题与解决方法概述

class Shape {
public:
    virtual void draw() const {
        cout << "Drawing a shape." << endl;
    }
};

class Rectangle : public Shape {
public:
    void draw() const override {
        cout << "Drawing a rectangle." << endl;
    }
};

void drawShape(const Shape& shape) {
    shape.draw();
}

int main() {
    Rectangle rectangle;
    drawShape(rectangle); // 正确示例

    shape.draw();
    return 0;
}

class Animal {
public:
    virtual void makeSound() const {
        cout << "Animal is making sound." << endl;
    }
};

class Dog : public Animal {
public:
    void makeSound() const override {
        cout << "Dog is barking." << endl;
    }
};

class Cat : public Animal {
public:
    void makeSound() const override {
        cout << "Cat is meowing." << endl;
    }
};

void perfORMSound(const Animal& animal) {
    if (const Dog* dog = dynamic_cast<const Dog*>(&animal)) {
        dog->makeSound();
    } else if (const Cat* cat = dynamic_cast<const Cat*>(&animal)) {
        cat->makeSound();
    } else {
        animal.makeSound();
    }
}

int main() {
    Dog dog;
    Cat cat;
    Animal animal;

    performSound(dog); // 输出："Dog is barking."
    performSound(cat); // 输出："Cat is meowing."
    performSound(animal); // 输出："Animal is making sound."

    return 0;
}