Copy Control Example

复制构造函数, 赋值操作符 operator = ,析构函数 总称为复制控制 (Copy Control)

e.g.:

Code:

#include <iostream>



using namespace std;



class T{

public:

    T(){ cout<<"T constructor."<<endl; }

    T(const T& tobj){

        cout<<" T copy construct from T:"<<&tobj<<endl;

        t=tobj.t;

    }

    //若声明为explicit,则隐式调用

     /*explicit */

    T(int tmp):t(tmp){

         cout<<"T constructor from int."<<tmp<<endl;

    }

    ~T(){   cout<<"T destructor. instance:"<<(int)this<<",t value:"<<t<<endl;   }

    T& operator =(const T& tobj){

        cout<<" operator =, from:"<<hex<<&tobj<<",to:"<<hex<<(int)this<<endl;

        this->t=tobj.t;

        return *this;

    }

    //前自加操作符

    T& operator ++(){

        ++t;

        return *this;

    }

    //后自加操作符

    T operator ++(int){

        T tmp(*this);

        ++ this->t;

        return tmp;

    }

    void print(){

        cout<<"addr:0x"<<hex<<(int)this<<".t="<<t<<endl;

    }

private:

    int t;

};





int main()

{

    T t=1;

    //t.print();

    t=2;    //生成一个临时对象 tmp(2),再调用operator =方法,将其值赋给t

    //t.print();

/*

    cout<<"T 自加之前"<<endl;

    t.print();

    ++t;

    cout<<"T 自加之后"<<endl;

    t.print();



    T t2=++t;

    t.print();

    t2.print();

*/

    cout<<"后加操作测试"<<endl;

    T t3= t++;

    t.print();

    t3.print();



    cin.get();

    return 0;

}