在C++中，类方法的继承和多态主要通过基类（父类）和派生类（子类）之间的关系来实现
继承：继承是面向对象编程的一个重要特性，它允许一个类（派生类）继承另一个类（基类）的属性和方法。这样，派生类可以重用基类的代码，同时还可以添加或覆盖基类的方法。
#include<iostream>class Base {public: void print() { std::cout << "Base class method"<< std::endl; }};class Derived : public Base {public: void print() { std::cout << "Derived class method"<< std::endl; }};int main() { Base *base = new Base(); base->print(); // 输出 "Base class method" Derived *derived = new Derived(); derived->print(); // 输出 "Derived class method" Base *base_ptr = new Derived(); base_ptr->print(); // 输出 "Base class method"，因为print()方法不是虚函数 delete base; delete derived; delete base_ptr; return 0;}多态是指允许使用基类指针或引用来操作派生类对象。为了实现多态，我们需要将基类的方法声明为虚函数（virtual）。这样，当通过基类指针或引用调用该方法时，会根据实际对象的类型来调用相应的方法。
#include<iostream>class Base {public: virtual void print() { std::cout << "Base class method"<< std::endl; }};class Derived : public Base {public: void print() override { std::cout << "Derived class method"<< std::endl; }};int main() { Base *base = new Base(); base->print(); // 输出 "Base class method" Derived *derived = new Derived(); derived->print(); // 输出 "Derived class method" Base *base_ptr = new Derived(); base_ptr->print(); // 输出 "Derived class method"，因为print()方法是虚函数 delete base; delete derived; delete base_ptr; return 0;}在这个例子中，我们将Base类的print()方法声明为虚函数。当我们通过Base类指针调用print()方法时，如果实际对象是Derived类的实例，那么将调用Derived类的print()方法。这就是多态的体现。
