面向对象程序设计实例——模拟网上购书的结帐功能

来源：互联网发布：苹果电脑软件推荐编辑：程序博客网时间：2024/05/18 02:26

首先得对这个问题进行分析，我们知道在网上买书的流程为输入会员号，如果不是会员则跳过，然后选择所要购买的书籍放如购书筐中，选择结束后，用户要求结帐，系统则根据用户的身份计算出他所需要付的钱数，整个系统很复杂，所以我在这里要解决的只是最后一步，既系统根据用户的身份计算出他所需要付的钱款。

因为有三种不同身份的人，但是他们又有共同之处，比如姓名，购书人编号，地址，购书金额，因此我们设计一个基类buyer类，其他的类layfolk（普通人），member（会员），honoured_guest（贵宾）均由它派生而出。基类中定义构造函数和对所有购书者相同的操作，函数getbuyername()用于得到购书者的姓名，getaddress()用于得到购书者的地址，getpay()用来取出购书者应付的金额，getid()用来取出购书者的编号。由于各类购书者的数据内容不同，显示方法也不一样，因此在基类中将setpay&display定义为虚函数。基类定义如下：

class buyer

{

protected:

char* name;

int buyerID;

char* address;

double pay;

public:

buyer();

buyer(char* n,int b,char* a,double p);

~buyer();

char* getbuyname();

int getid();

char* getaddress();

double getpay();

virtual void display()=0;

virtual void setpay(double=0)=0;

};

买书的过程中我们还需要得到关于书的一些基本情况，故我们还需要定义一个book类用来完成对书的一些基本操作。类book定义如下：

class book

{

protected:

char* bookID;

char* bookname;

char* auther;

char* publishing;

double price;

public:

book();

book(char* bid,char* bn,char* au,char* pu,double pr);

~book();

void display();

char* getbookID();

char* getbookname();

char* getauther();

char* getpublish();

double getprice();

};

在主函数中，我们建立了三个派生类的实例来证实程序的正确性，并假设已经选好两本书籍（book类对象），并将购书人的基本情况和书本的基本情况都显示出来，虽然在实际买书的过程中购书人的基本情况是不需要显示的，但我们将它显示出来只是为了证明程序的正确性和结果的可读性。

完整的程序如下：

//buy.h

#include <iostream.h>

#include <string.h>

class buyer

{

protected:

char* name;

int buyerID;

char* address;

double pay;

public:

buyer();

buyer(char* n,int b,char* a,double p);

~buyer();

char* getbuyname();

int getid();

char* getaddress();

double getpay();

virtual void display()=0;

virtual void setpay(double=0)=0;

};

class member:public buyer

{

int leaguer_grade;

public:

member(char* n,int b,int l,char* a,double p):buyer(n,b,a,p)

{leaguer_grade=l;}

void display();

void setpay(double p);

};

class honoured_guest:public buyer

{

double discount_rate;

public:

honoured_guest(char* n,int b,double r,char* a,double p):buyer(n,b,a,p)

{discount_rate=r;}

void display();

void setpay(double p);

};

class layfolk:public buyer

{

public:

layfolk(char* n,int b,char* a,double p):buyer(n,b,a,p)

{}

void display();

void setpay(double p);

};

buyer::buyer()

{

name=" ";

buyerID=0;

address=" ";

pay=0;

}

buyer::buyer(char* n,int b,char* a,double p)

{

name=new char[strlen(n)+1];

strcpy(name,n);

buyerID=b;

address=new char[strlen(a)+1];

strcpy(address,a);

pay=p;

}

buyer::~buyer()

{

delete [] name;

delete [] address;

}

double buyer::getpay()

{

return pay;

}

char* buyer::getaddress()

{

return address;

}

char* buyer::getbuyname()

{

return name;

}

int buyer::getid()

{

return buyerID;

}

void member::display()

{

cout<<"购书人姓名："<<name<<"/t";

cout<<"购书人编号："<<buyerID<<"/t";

cout<<"购书人地址："<<address<<"/t";

cout<<"购书人为会员，级别："<<leaguer_grade<<endl;

}

void member::setpay(double p)

{

if(leaguer_grade==1)

pay=0.95*p+pay;

else if(leaguer_grade==2)

pay=0.9*p+pay;

else if(leaguer_grade==3)

pay=0.85*p+pay;

else if(leaguer_grade==4)

pay=0.8*p+pay;

else if(leaguer_grade==5)

pay=0.7*p+pay;

else

cout<<"级别错误！";

}

void honoured_guest::display()

{

cout<<"购书人姓名："<<name<<"/t";

cout<<"购书人编号："<<buyerID<<"/t";

cout<<"购书人地址："<<address<<"/t";

cout<<"购书人为贵宾！折扣率为："<<discount_rate<<endl;

}

void honoured_guest::setpay(double p)

{

pay=pay+(1-discount_rate)*p;

}

void layfolk::display()

{

cout<<"购书人姓名："<<name<<"/t";

cout<<"购书人编号："<<buyerID<<"/t";

cout<<"购书人地址："<<address<<"/t";

cout<<"购书人为普通人"<<endl;

}

void layfolk::setpay(double p)

{

pay=pay+p;

}

//buy.h结束

//book.h

#include <iostream.h>

#include <string.h>

class book

{

protected:

char* bookID;

char* bookname;

char* auther;

char* publishing;

double price;

public:

book();

book(char* bid,char* bn,char* au,char* pu,double pr);

~book();

void display();

char* getbookID();

char* getbookname();

char* getauther();

char* getpublish();

double getprice();

};

book::book()

{

bookID=" ";

bookname=" ";

auther=" ";

publishing=" ";

price=0;

}

book::book(char* bid,char* bn,char* au,char* pu,double pr)

{

bookID=new char[strlen(bid)+1];

strcpy(bookID,bid);

bookname=new char[strlen(bn)+1];

strcpy(bookname,bn);

auther=new char[strlen(au)+1];

strcpy(auther,au);

publishing=new char[strlen(pu)+1];

strcpy(publishing,pu);

price=pr;

}

char* book::getbookID()

{

return bookID;

}

char* book::getbookname()

{

return bookname;

}

char* book::getauther()

{

return auther;

}

char* book::getpublish()

{

return publishing;

}

double book::getprice()

{

return price;

}

void book::display()

{

cout<<"书号："<<bookID<<endl;

cout<<"书名："<<bookname<<endl;

cout<<"作者："<<auther<<endl;

cout<<"出版社："<<publishing<<endl;

cout<<"定价:"<<price<<endl;

}

book::~book()

{

delete [] bookID;

delete [] bookname;

delete [] auther;

delete [] publishing;

}

//book.h结束

//主函数buybook.cpp

#include <iostream.h>

#include "buy.h"

#include "book.h"

void main()

{

int i=0,buyerid;

book *c[2];

layfolk b1("小王",1,"武汉",0);

honoured_guest b2("小李",2,0.6,"郑州",0);

member b3("小赵",3,5,"济南",0);

buyer *b[3]={&b1,&b2,&b3};

book c1("566-625-365","c++","richard","qinghua",25);

book c2("655-365-654","c","zihan","beida",39);

c[0]=&c1;

c[1]=&c2;

cout<<"购书人信息：/n/n";

for(i=0;i<3;i++)

b[i]->display();

cout<<"/n图书信息：/n/n";

for(i=0;i<2;i++)

c[i]->display();

cout<<"请输入购书人编号：";

cin>>buyerid;

for(i=0;i<3;i++)

if(b[i]->getid()==buyerid)

{

b[i]->setpay(c[0]->getprice());

b[i]->setpay(c[1]->getprice());

cout<<endl<<"购书人需要付费："<<b[i]->getpay()<<endl;

}

else

{

cout<<"错误的编号！"<<endl;

break;

}