C++中的多态和虚函数

    #include <iostream>
    using namespace std;
    //基类People
    class People{
    public:
        People(char *name, int age);
        void display();
    protected:
        char *m_name;
        int m_age;
    };
    People::People(char *name, int age): m_name(name), m_age(age){}
    void People::display(){
        cout<<m_name<<"今年"<<m_age<<"岁了，是个无业游民。"<<endl;
    }
    //派生类Teacher
    class Teacher: public People{
    public:
        Teacher(char *name, int age, int salary);
        void display();
    private:
        int m_salary;
    };
    Teacher::Teacher(char *name, int age, int salary): People(name, age), m_salary(salary){}
    void Teacher::display(){
        cout<<m_name<<"今年"<<m_age<<"岁了，是一名教师，每月有"<<m_salary<<"元的收入。"<<endl;
    }
    int main(){
        People *p = new People("王志刚", 23);
        p -&