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c++-在C++中出現的一個問題。

編輯：編程綜合問答

在C++中出現的一個問題。

在增添借閱者時輸入學號後退出，求助，謝謝。

 #include <iostream> 
using namespace std;
#include <string> 
#include <fstream>
#include <iomanip>  


const int Maxr=300; 

const int Maxb=300; 

const int Maxbor=10;








class Reader 
{ 
private: 
int tag; 
int No; 
char name[20]; 
int borbook[Maxbor]; 
public: 
Reader() {} 
char *getname() {return name;} 
int gettag() {return tag;}  
int getno() {return No;} 

void setname(char na[]) 
{ 
strcpy(name,na); 
} 
void delbook(){ tag=1; } 
void addreader(int n,char *na) 
{ 
tag=0; 
No=n; 
strcpy(name,na); 
for(int i=0;i<Maxbor;i++) 
borbook[i]=0;
} 
void borrowbook(int bookid)
{   
for(int i=0;i<Maxbor;i++) 
{ 
if (borbook[i]==0) 
{ 
borbook[i]=bookid; 
return; 
} 
} 
} 
int retbook(int bookid) 
{ 
for(int i=0;i<Maxbor;i++) 
{ 
if(borbook[i]==bookid) 
{ 
borbook[i]=0; 
return 1; 
} 
} 
return 0; 
} 
void disp() 
{ 
cout << setw(10) << No <<setw(15) << name<<"借書檢索號：[";
for(int i=0;i<Maxbor;i++) 
if(borbook[i]!=0) 
cout << borbook[i] << "|"; 
cout << "]"<<endl; 
} 
}; 
class RDatabase 
{ 
private: 
    int top; 
Reader read[Maxr]; 
public: 
RDatabase() 
{ 
Reader s; 
top=-1;
fstream file("reader.txt",ios::in);  
while (1) 
{ 
file.read((char *)&s,sizeof(s)); 
if (!file)break;
top++; 
read[top]=s; 
} 
file.close(); 
} 
void clear() 
{ 
top=-1; 
} 
int addreader(int n,char *na) 
{ 
Reader *p=query(n); 
if (p==NULL) 
{ 
top++; 
read[top].addreader(n,na); 
return 1; 
} 
return 0; 
} 
Reader *query(int readerid) 
{ 
for (int i=0;i<=top;i++) 
if (read[i].getno()==readerid && 
read[i].gettag()==0) 
{ 
return &read[i];  
} 
return NULL; 
} 
void disp() 
{ 
for (int i=0;i<=top;i++) 
read[i].disp(); 
}
void readerdata(); 
~RDatabase() 
{ 
fstream file("reader.txt",ios::out); 
for (int i=0;i<=top;i++) 
if (read[i].gettag()==0) 
file.write((char *)&read[i],sizeof(read[i])); 
file.close(); 
} 
}; 
void RDatabase::readerdata() 
{ 
char choice; 
char rname[20]; 
int readerid; 
Reader *r; 




cout <<"\n\n\t\t\t借閱者信息\n\n\n\t\t 1 增加借閱者信息\n\n\t\t 2 修改借閱者信息\n\n\t\t 3 刪除借閱者信息\n\n\t\t 4 查詢借閱者信息\n\n\t\t 0 退出"<<endl; 
cin >> choice; 
switch (choice) 
{ 
case '1': 
cout << "輸入借閱者學號:"; 
cin >> readerid; 
cin >> rname; 
addreader (readerid,rname); 
break; 
case '2': 
cout << "輸入借閱者學號:"; 
cin >> readerid; 
 r=query(readerid); 
if (r==NULL) 
cout << " 借閱者信息錯誤"<<endl; 
break; 

cout << "重新輸入姓名:"; cin >> rname;
r->setname(rname); 
break; 
case '3': 
    cout << " 輸入借閱者學號:"; 
cin >> readerid; r=query(readerid); 
if (r==NULL) 
cout <<" 借閱者信息錯誤" << endl; 
break; 
r->delbook(); 
break;
case '4': 
cout << "輸入借閱者學號:"; 
cin >> readerid; 
r=query(readerid); 
if (r==NULL) 
{ 
cout <<"學號信息錯誤"<< endl; 
} r->disp(); 
break; 
break; 
case '5': 
disp(); 
break; 

default:cout<<"信息錯誤，請重新輸入：";
    break; 
} 
} 

class Book 
{ 
private: 
float price; 
char author[10]; 
int tag; 
int No; 
char place[40];
char name[20]; 
int onshelf; 
public: 
Book(){} 
char *getname() { return name; } 
int getNo(){ return No; } 
char *getplace(){ return place;}
int gettag(){ return tag; } 
char*getauthor(){return author;} 
char getprice(){return price;} 
void setname(char na[]) 
{ 
strcpy(name,na); 
} 
void setauthor(char au[]) 
{ 
strcpy(author,au);} 
void delbook(){ tag=1;} 
void addbook(int N,char *na,char*au,int pr,char *bp)
{ 
tag=0; 
No=N; 
price=pr; 
strcpy(author,au); 
strcpy(name,na); 
onshelf=1; 
} 
int borrowbook() 
{ 
if (onshelf==1) 
{ 
onshelf=0; 
return 1; 
} 
return 0; 
} 
void retbook() 
{ 
onshelf=1; 
} 
void disp() 
{ 
cout<< setw(6)<< "檢索號: " << No << setw(18) <<"書名: "<< name << setw(10) <<"作者: "<<author<<setw(18)<<"單價: "<<price<<setw(10) <<(onshelf==1? "有現存":"已借完") <<endl; 
} 
};  
class BDatabase 
{ 

private: 
int top;
Book book[Maxb]; 
public: 
BDatabase() 
{ 
Book b; 
top=-1; 
fstream file("book.txt",ios::in); 
while (1) 
{ 
file.read((char *)&b,sizeof(b)); 
if (!file) break; 
top++; 
book[top]=b; 
} 
file.close(); 
} 
void clear() 
{ 
top=-1; 
} 
int addbook(int n,char *na,char*au,int pr,char *bp) 
{ 
Book *p=query(n); 
if (NULL==p) 
{ 
top++; 
book[top].addbook(n,na,au,pr,bp); 
return 1; 
} 
return 0; 
} 
Book *query(int bookid) 
{ 
for (int i=0;i<=top;i++) 
if (book[i].getNo()==bookid &&book[i].gettag()==0) 
{ 
return &book[i]; 
} 
return NULL; 
} 
void bookdata(); 
void disp() 
{ 
for (int i=0;i<=top;i++) 
if (book[i].gettag()==0) 
book[i].disp(); 
} 
~BDatabase() 
{ 
fstream file("book.txt",ios::out); 
for (int i=0;i<=top;i++) 
if (book[i].gettag()==0) 
file.write((char *)&book[i],sizeof(book[i])); 
file.close(); 
} 
}; 
void BDatabase::bookdata() 
{ 
char choice; 
char bauthor[10];
int bprice; 
char bname[40]; 
int bookid; 
char bplace[40];
Book *b; 



cout <<"\n\n\n\t\t\t圖書信息"<<endl<<endl; cout<<"\t\t1 增加圖書信息\n \t\t2 修改圖書信息\n\t\t3 刪除圖書信息\n\t\t4 查詢圖書信息\n\t\t0 退出"<<endl; 
cin >> choice; 
switch (choice) 
{ 
case '1': 
cout << "輸入圖書檢索號:"<<endl; 
cin >> bookid; 
cout << "輸入圖書書名:"<<endl; 
cin >> bname; 
cout<<" 輸入作者名:"; 
cin>>bauthor;
cout << "輸入圖書價格:"<<endl; 
cin >> bprice; 
cout << "輸入圖書出版社:"<<endl; 
cin >> bplace; 
addbook(bookid,bname,bauthor,bprice,bplace); 
break;
case '2': 
cout << "輸入圖書檢索號:"<<endl; 
cin >> bookid; 
b=query(bookid); 
if (b==NULL) 
{ 
cout << " 信息錯誤"<<endl; 
break; 
} 
cout << "重新輸入書名:"<<endl; 
cin >> bname; 
b->setname(bname); 
break; 
case '3': 
cout <<" 讀入圖書檢索號:"<<endl; 
cin >> bookid; 
b=query(bookid); 
if (b==NULL) 
{ 
cout <<" 信息錯誤" << endl; 
break; 
} 
b->delbook(); 
break; 
case '4': 
cout << " 讀入圖書檢索號:"<<endl; 
cin >> bookid; 
b=query(bookid); 
if (b==NULL) 
{ 
cout <<" 信息錯誤"<< endl; 
break; 
} 
b->disp(); 
break; 

default:cout<<"信息錯誤，請重新輸入:"; 
} 
} 

void main()
{ 
char choice; 
int bookid,readerid; 
RDatabase ReaderDB; 
Reader *r; 
BDatabase BookDB; 
Book *b; 



cout <<endl<<endl<<"\t\t\t 圖書管理系統\n\n\n"; 

cout <<"\t\t\t1 借還情況\n\n\t\t\t2 圖書信息表\n\n\t\t\t3 借閱者信息表\n\n\t\t\t0 退出"<<endl; 
cin >> choice; 
switch (choice) 
{ 
case '1': 
cout <<"\t\t\t1 借書\n\n\t\t\t2 還書\n\n\t\t\t0 退出"<<endl;
cin>>choice;
switch(choice)
{

case '1':
cout <<" 借閱者學號:"; 
cin >>readerid; 
cout <<" 圖書檢索號："; 
cin >>bookid; 
r=ReaderDB.query(readerid); 
if (NULL==r) 
{ 
cout <<" 借閱者信息錯誤，不能借書"<< endl; 
break; 
} 
b=BookDB.query(bookid); 
if (b==NULL) 
{ 

    cout<<"圖書信息錯誤，不能借書"<<endl;
    break;
}
if(b->borrowbook()==0)
{
    cout<<"該圖書沒有現存，不能借書"<<endl;
    break;
}
r->borrowbook(b->getNo());
break;
case '2':
    cout<<"借閱者學號:";
    cin>>readerid;
    cout<<"圖書檢索號：";
    cin>>bookid;
    r=ReaderDB.query(readerid);
    if(r==NULL)
    {
        cout<<"借閱者信息錯誤，不能還書"<<endl;
        break;
    }
    b=BookDB.query(bookid);
    if(b==NULL)
    {
        cout<<"圖書信息錯誤，不能還書"<<endl;
        break;
    }
    b->retbook();
    r->retbook(b->getNo());
    break;
}



case '2':
    BookDB.bookdata();
break; 
case '3': 
ReaderDB.readerdata(); 
break; 
default:cout<<"信息錯誤，請從新輸入："; 
} 
}