C++ 泛型编程中如何处理运行时类型信息？

class Base { };
class Derived : public Base { };

int main() {
  Base* base_ptr = new Derived();

  // 检查 base_ptr 是否指向 Derived 对象
  Derived* derived_ptr = dynamic_cast<Derived*>(base_ptr);
  if (derived_ptr != nullptr) {
    // 转换成功，base_ptr 指向 Derived 对象
  }
}

class Base { };
class Derived : public Base { };

int main() {
  Base obj;
  std::cout << typeid(obj).name() << std::endl; // 输出：Base

  // 检查 obj 是否属于 Derived 类型
  if (typeid(obj).before(typeid(Derived))) {
    std::cout << "obj is not a Derived object" << std::endl;
  }
}

class Shape {
public:
  virtual void draw() = 0;
};

class Circle : public Shape {
public:
  void draw() override {
    std::cout << "Drawing a circle" << std::endl;
  }
};

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

class Triangle : public Shape {
public:
  void draw() override {
    std::cout << "Drawing a triangle" << std::endl;
  }
};

int main() {
  std::vector<Shape*> shapes{new Circle, new Rectangle, new Triangle};

  for (auto shape : shapes) {
    // 使用 RTTI 获取形状类型
    std::cout << "Drawing a " << typeid(*shape).name() << std::endl;

    // 根据类型调用相应的方法
    shape->draw();
  }
}

Drawing a Circle
Drawing a Rectangle
Drawing a Triangle