File I/O

[DrEaMzLeDS]

Somebody help me with my project.
All of the options work except for the "delete" book option.
Whenever I use this code/function:

system("erase bookfile.txt ");
getch();
system("rename tempfile.txt bookfile.txt");

when compiled, it becomes an error.
But when removed & compiled, it works but can't delete a file.
Btw, I'm using C++ Borland Ver. 4.5. I know it's an outdated version but my school strictly implements that we must use only this.

Here is the Source Code

#include <iostream.h>
#include <fstream.h>
#include <conio.h>
#include <iomanip.h>
#include <stdio.h>
#include <string.h>
#pragma pack (2)

int menu();
class Book
{
private:
int bookid;
char title[20];
float price;
protected:
int allotbookid();
void showheader();
public:
void getbook();
void showbook();
void addbook();
void viewbook();
void searchbook();
void deletebook();
void modifybook();
};
int Book::allotbookid()
{
ifstream fin;
Book temp;
int id=0;
fin.open("bookfile.txt",ios::in|ios::binary);
if(!fin)
return(id+1);
else
{
fin.read((char*)&temp,sizeof(temp));
while(!fin.eof())
{
id=temp.bookid;
fin.read((char*)&temp,sizeof(temp));
}
id++;
return(id);
}
}


void Book::showheader()
{

cout<<"\n"<<setw(10)<<"BOOK ID"<<setw(10)<<"Price"<<setw(10)<<"Title\n";
}
void Book::getbook()
{
cout<<"Enter Book Title: ";
fflush(stdin);
gets(title);
cout<<"Price of Book: ";
cin>>price;
bookid=allotbookid();
}
void Book::showbook()
{

cout<<"\n"<<setw(10)<<bookid<<setw(10)<<price<<setw(10)<<title;
}
void Book::addbook()
{
ofstream fout;
fout.open("bookfile.txt",ios::out|ios::app|ios::binary);
if(!fout)
cout<<"File can not open";
else
fout.write((char*)this,sizeof(*this));
fout.close();
}
void Book::viewbook()
{
ifstream fin;
fin.open("bookfile.txt",ios::in|ios::binary);
if(!fin)
cout<<"File not found";
else
{
showheader();
fin.read((char*)this,sizeof(*this));
while(!fin.eof())
{
showbook();
fin.read((char*)this,sizeof(*this));
}
}
fin.close();
}
void Book::searchbook()
{
ifstream fin;
char str[20];
fin.open("bookfile.txt",ios::in|ios::binary);
cout<<"Enter the name of book to search:";
fflush(stdin);
gets(str);
if(!fin)
cout<<"File not found";
else
{
fin.read((char*)this,sizeof(*this));
while(!fin.eof())
{

if(!strcmp(this->title,str))
{
showheader();
showbook();
break;
}
fin.read((char*)this,sizeof(*this));
}
if(fin.eof())
cout<<"\nRecord not found";
}
fin.close();
}
void Book:: modifybook()
{
int id,r=0;
fstream file;
file.open("bookfile.txt",ios::in|ios::out|ios::ate|ios::binary);
cout<<"\nEnter record number to modify (book ID): ";
cin>>id;
file.seekg(0);
if(!file)
cout<<"File not found";
else
{
file.read((char*)this,sizeof(*this));

while(!file.eof())
{
r++;
if(bookid==id)
{
showheader();
showbook();
cout<<"\nRe-enter book details:\n";
cout<<"Enter book title: ";
fflush(stdin);
gets(title);
cout<<"Enter book price: ";
cin>>price;
file.seekp((r-1)*sizeof(Book),ios::beg);
file.write((char*)this,sizeof(*this));
break;
}
file.read((char*)this,sizeof(*this));
}
if(file.eof())
cout<<"Record not found";
}
file.close();
}
void Book:: deletebook()
{
ifstream fin;
ofstream fout;
int id;
char x;
fin.open("bookfile.txt",ios::in|ios::binary);
fout.open("tempfile.txt",ios::out|ios::app|ios::binary);
cout<<"Enter book ID to delete record: ";
cin>>id;
if(!fin)
cout<<"File not found";
else
{
fin.read((char*)this,sizeof(*this));
while(!fin.eof())
{
if(this->bookid==id)
{
cout<<"Record you want to delete is:\n\n";
showheader();
showbook();
cout<<"\nAre you sure you want to delete this record(y/n): ";
fflush(stdin);
cin>>x;
if(x=='n')
fout.write((char*)this,sizeof(*this));
else
cout<<"\nRecord is deleted";
}
else
fout.write((char*)this,sizeof(*this));
fin.read((char*)this,sizeof(*this));
}
fin.close();
fout.close();


system("erase bookfile.txt ");
getch();
system("rename tempfile.txt bookfile.txt");

getch();



}
}
int menu()
{
cout<<"\t\t\tBethesda Corp.\n";
cout<<"\t\t\tNacorda's Bookshop"<<endl;
cout<<"\n\t1. Add new book";
cout<<"\n\t2. View all books";
cout<<"\n\t3. Search book";
cout<<"\n\t4. Modify book";
cout<<"\n\t5. Delete book";
cout<<"\n\t6. Exit";
cout<<"\n\n\tEnter your choice: ";
int ch;
cin>>ch;
return(ch);
}
int main()
{
clrscr();
Book b;
int ch;
while(1)
{
ch=menu();
switch(ch)
{
case 1:
b.getbook();
b.addbook();
break;
case 2:
b.viewbook();
break;
case 3:
b.searchbook();
break;
case 4:
b.modifybook();
break;
case 5:
b.deletebook();
break;
case 6:
cout<<"\t\tThank you and Enjoy your Book!\n";
cout<<"\t\t\tPls Come Again!\n";
break;


default:
cout<<"Enter Valid choice";
}
getch();
clrscr();
}
}


PLS PLS PLS somebody help me.
This project is due in 12 hrs and I don't know what to do.
Pls help ASAP!!!
>.<

[LB]

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