C++学习笔记28:运行期型式信息

//programmer类是Employee的派生类
#include <typeinfo>
Programmer P;
Employee &e = P;
//输出P实际类名的字符串“programmer”
cout << typeid(e).name() << endl;

class Employee
{
public:
    virtual void PaySalary();
    virtual void PayBonus();
};
class Manager :public Employee
{
public:
    virtual void PaySalary();
    virtual void PayBonus();
};
class Programmer :public Employee
{
public:
    virtual void PaySalary();
    virtual void PayBonus();
};
class Company
{
public:
    virtual void PayRoll(Employee *e);
    virtual void PayRoll(Employee &e);
private:
    vector<Employee *> _employees;//向量保存雇员
};
void Company::PayRoll(Employee *e)//版本1
{
    //调用哪个成员函数，如何区分程序员和经理
    e->PaySalary();
    e->PayBonus();
}
void Company::PayRoll(Employee *e)//版本2
{
    Programmer *p = dynamic_cast<Programmer *>(e);
    if (p)    //p确实指向程序员对象
    {
        p->PaySalary();
        p->PayBonus();
    }
    else//p不指向程序员，不发奖金
    {
        e->PaySalary();
    }
}
void Company::PayRoll(Employee &e)//版本3
{
    try
    {
        Programmer &p = dynamic_cast<Programmer&>(e);
        p.PaySalary();
        p.PayBonus();
    }
    catch (std::bad_cast)
    {
        e.PaySalary();
    }
}