RTTI的魅力（运行时类型识别 Run-time type Identification）

一句话总结：实际运行时检查指针或者引用指向的实际派生类型。

两个重要的哼哈二将：typeid、dynamic_cast

#ifndef CRTTI_hpp

#define CRTTI_hpp

#include <iostream>

class CPerson

{

public:

    void getup(){std::cout<<"getup..."<<std::endl;}

    void sleep(){std::cout<<"sleep..."<<std::endl;}

    virtual ~CPerson(){}//这个很重要，没有这个，RTTI就不要玩了

public:

    int age;

    int tall;

};

class CFarmer: publicCPerson

{

public:

    void farming(){std::cout<<"farming..."<<std::endl;};

};

class CWorker: publicCPerson

{

public:

    void building(){std::cout<<"building..."<<std::endl;};

};

#endif /* CRTTI_hpp */

#include <iostream>

#include "CRTTI.hpp"

using namespacestd;

void doAction(CPerson* obj)

{

    cout<<typeid(*obj).name()<<endl;

    obj->getup();

    if (typeid(*obj) ==typeid(CFarmer))
{

        CFarmer* farmer =dynamic_cast<CFarmer*>(obj);

        farmer->farming();

    }

    else{

        cout<<"who are you"<<endl;

    }

    obj->sleep();

}

int main(int argc,const
char * argv[]) {

    // insert code here...

    CFarmer farmer;

    doAction(&farmer);

    CWorker *worker =new
CWorker();

    doAction(worker);

    delete worker;

    return0;

}

运行结果：

7CFarmer

getup...

farming...

sleep...

7CWorker

getup...

who are you

sleep...

Program ended with exit code: 0

dynamic_cast注意事项：

1、只能应用于指针和引用之间的转换

2、要转换的类型中必须包含虚函数

3、转换成功返回子类的地址，失败返回null

typeid注意事项：

1、type_id返回一个type_info对象的引用

2、基类必须带有虚函数，否则通过基类获得的数据类型依旧是基类