class Cd
{
private:
    char * performers;
    char * label;
    int selections;
    double playtime;
public:
    Cd(const char * s1,const char * s2,int n,double x);
    Cd(const Cd & d);
    Cd();
    ~Cd();
   virtual void Report()const;
    Cd & operator=(const Cd & d);
};

class Classic: public Cd
{
private:
    char * musicstr;

public:
    Classic(const char * mu="none",const char * s1="null name",const char * s2="null label",int n=0,double x=0.0);
    Classic(const char * mu,const Cd & c);
    Classic(const Classic & s);
    Classic & operator=(const Classic & s);

    ~Classic();
     virtual void Report()const;
};


Cd & Cd::operator=(const Cd & d)
{
    if(this==&d)
        return *this;
    delete [] performers;//1
    delete [] label;//2
    performers=new char[strlen(d.performers)+1];
    label=new char[strlen(d.label)+1];
    strcpy(performers,d.performers);
    strcpy(label,d.label);
    selections=d.selections;
    playtime=d.playtime;
    return *this;
}


Classic & Classic::operator=(const Classic & s)
{
    if(this==&s)
        return *this;
    
    Cd::operator =(s);
         delete [] musicstr;//需要和//1、//2一样删除之前的指针成员内存后在分配空间吗？                                 
    musicstr=new char[strlen(s.musicstr)+1];
    strcpy(musicstr,s.musicstr);
    return *this;
}

#include<iostream>
using namespace std;
#include"cd.h"
void Bravo(const Cd & disk);
int main()
{
    Cd c1("Beatles","Capitol",14,35.5);
    Classic c2=Classic("Piano Sonata in B flat,Fantasia in C",
        "Alfred Brendel","Philips",2,57.17);

    Cd * pcd=&c1;

    cout<<"Using object directly: \n";
    c1.Report();
    c2.Report();

    cout<<"Using type cd * pointer to objects: \n";
    pcd->Report();
    pcd=&c2;
    pcd->Report();

    cout<<"Calling a function with a Cd reference argument: \n";
    Bravo(c1);
    Bravo(c2);
    cout<<"Testing assignment: ";
    Classic copy;
    copy=c2;//对应那个delete [] musicstr;需要加delete [] musicstr;这样做吗？
    copy.Report();

    return 0;
}

void Bravo(const Cd & disk)
{
    disk.Report();
}

[[it] 本帖最后由 沿途有鬼 于 2008-8-17 12:54 编辑 [/it]]