作业一

//图书信息
class book
{
public:
    void writet(const char *filename);                 //添加图书信息
    void readt(const char *filename);                  //读取图书信息
    void delt(const char *filename);                   //删除图书信息
    int search_post(const char *filename,int id);      //搜索图书信息
    void searcht(const char *filename);                //查看图书信息
    void editt(const char *filename);                  //修改图书信息
};


void book::writet(const char *filename)                 //添加图书信息
{
    ofstream out;
    out.open("books.txt",ios::app);
    if(!out.is_open())
    {
        cout<<"open error"<<endl;
        return ;
    }
    else
    {
        int id;
        string name,author,publishing;
        double price;
        cout<<"请输入id、书名、作者、出版社、价格："<<endl;
        cin>>id>>name>>author>>publishing>>price;
        out.fill(' ');
        out.setf(ios::left);
        out<<space<<id<<space<<name<<space<<author<<space<<publishing<<space<<price<<NEWLINE;
        out.close();
        cout<<"添加成功！！"<<endl;
    }
}

void book::readt(const char *filename)                   //读取图书信息
{
    ifstream in;
    in.open("books.txt",ios::in);
    if(!in.is_open())
    {
        cout<<"file open error"<<endl;
        return ;
    }
    else
    {
        stringstream ss;   //创建存储str的副本的 stringstream 对象，其中str是 string 类型的对象
        char line[100];
        cout.setf(ios::left);
        cout.fill(' ');    //用空格填充
        cout<<space<<"id"<<space<<"name"<<space<<"author"<<space<<"publishing"<<space<<"price"<<endl;
        while(in.peek()!=EOF)
        {
            in.getline(line,100);
            ss<<line;
            int id;
            string name,author,publishing;
            double price;
            ss>>id>>name>>author>>publishing>>price;
            cout<<setw(20)<<id<<setw(20)<<name<<setw(20)<<author<<setw(20)<<publishing<<setw(20)<<price<<endl;
            ss.str("");                   //用""给ss赋值
            ss.clear();                   //清空字符串
        }
        in.close();
    }
}


void book::delt(const char *filename)        //删除图书信息    
{
    int id;
    cout<<"请输入您要删除图书的编号"<<endl;
    cin>>id;
    ifstream in;
    in.open("books.txt",ios::in);
    if(!in.is_open())
    {
        cout<<"file open error"<<endl;
        return ;
    }
    else
    {
        string temp;
        stringstream ss;
        int curId;;
        while(in.peek()!=EOF)
        {
            string line;
            getline(in,line);
            ss<<line;
            ss>>curId;
            if(curId!=id)
            {
                temp += line + NEWLINE;
            }
            ss.str("");
            ss.clear();
        }
        in.close();
        ofstream out;
        out.open("books.txt",ios::out);
        if(!out.is_open())
        {
            cout<<"file open error"<<endl;
            return ;
        }
        else
        {
            out<<temp;
            out.close();
            cout<<"删除成功！！"<<endl;
        }
    }
}


int book::search_post(const char *filename,int id)  //搜索图书信息
{
    ifstream in;
    in.open("books.txt",ios::in|ios::binary);
    if(!in.is_open())
    {
        cout<<"file open error"<<endl;
        return -1;
    }
    else
    {
        stringstream ss;
        while(in.peek()!=EOF)
        {
            int start = in.tellg();
            string line;
            getline(in,line);
            ss<<line;
            int curID;
            ss>>curID;
            if(curID == id)
            {
                in.close();
                return start;
            }
            ss.str("");
        }
        cout<<"对不起您查找的图书信息不存在!"<<endl;
        in.close();
    }
    return -1;
}


void book::searcht(const char *filename)         //查看图书信息           
{
    cout<<"请输入您要查找的图书id："<<endl;
    int id;
    cin>>id;
    int pos = search_post("books.txt",id);
    string line;
    fstream in;
    in.open("books.txt",ios::in|ios::binary);
    in.seekg(pos,ios::beg);
    getline(in,line);
    cout.setf(ios::left);
    cout<<setw(13)<<"id"<<setw(20)<<"name"<<setw(15)<<"author"<<setw(15)<<"publishing"<<setw(15)<<"price"<<endl;
    cout<<line<<endl;
}


void book::editt(const char *filename)      //修改图书信息         
{
    int id;
    string name,author,publishing;
    double price;
    cout<<"请输入您要修改的图书id"<<endl;
    cin>>id;
    cout<<"请输入该图书新的书名、作者、出版社、价格"<<endl;
    cin>>name>>author>>publishing>>price;
    stringstream infoTemp;
    infoTemp.fill(' ');
    infoTemp.setf(ios::left);
    infoTemp<<space<<id<<space<<name<<space<<author<<publishing<<price;
    string newInfo;
    getline(infoTemp,newInfo);
    fstream file;
    file.open("books.txt",ios::in|ios::out|ios::binary);
    if(!file.is_open())
    {
        cout<<"file open error"<<endl;
        return ;
    }
    else
    {
        int pos = search_post("books.txt",id);
        file.seekg(pos,ios::beg);
        file<<newInfo;
        cout<<"修改后信息为："<<endl;
        cout<<newInfo<<endl;
        file.close();
    }
}






用户
class buyer
{
public:
    void ready(const char *filename);                   //读取用户信息
    void dely(const char *filename);                    //删除用户信息
    int search_posy(const char *filename,int id);       //搜索用户信息
    void searchy(const char *filename);                 //查找用户信息
    void readd(const char *filename);                   //查看订单信息
};



void buyer::ready(const char *filename)                   //读取用户信息
{
    ifstream in;
    in.open("users.txt",ios::in);
    if(!in.is_open())
    {
        cout<<"file open error"<<endl;
        return ;
    }
    else
    {
        stringstream ss;   //创建存储str的副本的 stringstream 对象，其中str是 string 类型的对象
        char line[100];
        cout.setf(ios::left);
        cout.fill(' ');    //用空格填充
        cout<<space<<"id"<<space<<"name"<<space<<"address"<<space<<"会员等级"<<endl;
        while(in.peek()!=EOF)
        {
            in.getline(line,100);
            ss<<line;
            int id,meg;
            string name,address;
            ss>>id>>name>>address>>meg;
            cout<<space<<id<<space<<name<<space<<address<<space<<meg<<endl;
            ss.str("");                   //用""给ss赋值
            ss.clear();                   //清空字符串
        }
        in.close();
    }
}


void buyer::dely(const char *filename)             //删除用户信息       
{
    int id;
    cout<<"请输入您要删除用户的编号"<<endl;
    cin>>id;
    ifstream in;
    in.open("users.txt",ios::in);
    if(!in.is_open())
    {
        cout<<"file open error"<<endl;
        return ;
    }
    else
    {
        string temp;
        stringstream ss;
        int curId;;
        while(in.peek()!=EOF)
        {
            string line;
            getline(in,line);
            ss<<line;
            ss>>curId;
            if(curId!=id)
            {
                temp += line + NEWLINE;
            }
            ss.str("");
            ss.clear();
        }
        in.close();
        ofstream out;
        out.open("users.txt",ios::out);
        if(!out.is_open())
        {
            cout<<"file open error"<<endl;
            return ;
        }
        else
        {
            out<<temp;
            out.close();
            cout<<"删除成功！！"<<endl;
        }
    }

}



int buyer::search_posy(const char *filename,int id)     //搜索用户信息
{
    ifstream in;
    in.open("users.txt",ios::in|ios::binary);
    if(!in.is_open())
    {
        cout<<"file open error"<<endl;
        return -1;
    }
    else
    {
        stringstream ss;
        while(in.peek()!=EOF)
        {
            int start = in.tellg();
            string line;
            getline(in,line);
            ss<<line;
            int curID;
            ss>>curID;
            if(curID == id)
            {
                in.close();
                return start;
            }
            ss.str("");
        }
        cout<<"对不起您查找的用户信息不存在!"<<endl;
        in.close();
    }
    return -1;
}


void buyer::searchy(const char *filename)                 //查找用户信息           
{
    cout<<"请输入您要查找的用户id："<<endl;
    int id;
    cin>>id;
    int pos = search_posy("users.txt",id);
    string line;
    fstream in;
    in.open("users.txt",ios::in|ios::binary);
    in.seekg(pos,ios::beg);
    getline(in,line);
    cout.setf(ios::left);
    cout<<setw(12)<<"id"<<setw(14)<<"name"<<setw(14)<<"address"<<setw(12)<<"会员等级"<<endl;
    cout<<line<<endl;
}


void buyer::readd(const char *filename)         //查看用户信息           
{
    ifstream in;
    in.open("orders.txt",ios::in);
    if(!in.is_open())
    {
        cout<<"file open error"<<endl;
        return ;
    }
    else
    {
        stringstream ss;   //创建存储str的副本的 stringstream 对象，其中str是 string 类型的对象
        char line[100];
        cout.setf(ios::left);
        cout.fill(' ');    //用空格填充
        while(in.peek()!=EOF)
        {
            in.getline(line,100);
            ss<<line;
            int id;
            string name,author,publishing;
            double price;
            ss>>id>>name>>author>>publishing>>price;
            cout<<space<<id<<space<<name<<space<<author<<space<<publishing<<space<<price<<endl;
            ss.str("");                   //用""给ss赋值
            ss.clear();                   //清空字符串
        }
        in.close();
    }
}  




订单
class order
{
protected:
    double pay;                         //购书金额
public:
    order();
    //购书功能
    int find_user(const char *filename,int id);   //将用户信息输入到订单信息中
    int find_book(const char *filename,int id);   //将图书信息输入到订单信息中
    void options1();         //选购图书
    int search_poso(const char *filename,int id);  //搜索订单信息
    void searcho(const char *filename);            //查找订单信息
};

order::order()
{
    pay=0;
}

int order::find_user(const char *filename,int id)
{
    ofstream outfile;      
    outfile.open("orders.txt", ios::app);
    outfile<<endl;
    ifstream in;
    in.open("users.txt",ios::in|ios::binary);
    if(!in.is_open())                          //将购书的用户信息输入到订单中
    {
        cout<<"file open error"<<endl;
        return -1;
    }
    else
    {
        stringstream ss;
        while(in.peek()!=EOF)
        {
            int start = in.tellg();
            string line;
            getline(in,line);
            outfile<<line;
            outfile.close();
            ss<<line;
            int curID;
            ss>>curID;
            if(curID == id)
            {
                in.close();
                return start;
            }
            ss.str("");
        }
        cout<<"对不起您查找的图书信息不存在!"<<endl;   
    }
    return -1;
}


int order::find_book(const char *filename,int id)
{
    ofstream outfile;      
    outfile.open("orders.txt", ios::app);
    ifstream in;
    in.open("books.txt",ios::in|ios::binary);
    if(!in.is_open())                          //将购买的图书信息输入到订单中
    {
        cout<<"file open error"<<endl;
        return -1;
    }
    else
    {
        stringstream ss;
        while(in.peek()!=EOF)
        {
            int start = in.tellg();
            string line;
            getline(in,line);
            outfile << line;
            outfile.close();
            ss<<line;
            int curID;
            ss>>curID;
            if(curID == id)
            {
                in.close();
                return start;
            }
            ss.str("");
        }
        cout<<"对不起您查找的图书信息不存在!"<<endl;   
    }
    return -1;
}

void order::options1()  //选购图书 
{
    int p;
    cout<<"请输入用户编号："; 
    cin>>p;
    cout<<endl;
    find_user("users.txt",p);
    int q;
    cout<<"请输入书编号："; 
    cin>>q;
    cout<<endl;
    find_book("books.txt",q);
//    options1();
}

int order::search_poso(const char *filename,int id)  //搜索订单信息
{
    ifstream in;
    in.open("orders.txt",ios::in|ios::binary);
    if(!in.is_open())
    {
        cout<<"file open error"<<endl;
        return -1;
    }
    else
    {
        stringstream ss;
        while(in.peek()!=EOF)
        {
            int start = in.tellg();
            string line;
            getline(in,line);
            ss<<line;
            int curID;
            ss>>curID;
            if(curID == id)
            {
                in.close();
                return start;
            }
            ss.str("");
        }
        cout<<"对不起您查找的订单信息不存在!"<<endl;
        in.close();
    }
    return -1;
}


void order::searcho(const char *filename)                      
{
    cout<<"请输入您要查找的用户id："<<endl;
    int id;
    cin>>id;
    int pos = search_poso("orders.txt",id);
    string line;
    fstream in;
    in.open("orders.txt",ios::in|ios::binary);
    in.seekg(pos,ios::beg);
    getline(in,line);
    cout.setf(ios::left);
    cout<<line<<endl;
}

我选的是 购书系统，在进行第一次测试时出现无法显示所购买的图书信息；如果所查找的图书不存在则无提示直接退出；无删除用户信息此功能。针对此问题他们进行了如上修改。结合课本上的知识，该程序多用存储继承完成。以后在编程中我们要有紧密的逻辑思路，对所做项目要考虑周全。