Binary File Handling

#include<fstream.h>
#include<conio.h>
#include<stdio.h>
#include<stdlib.h>
class BOOK
{
    int b_no;
    char b_name[50];
    public:
    void getdetails()
    {
        cout<<"\n Enter book no.: ";
        cin>>b_no;
        cout<<"\n Enter book name: ";
        gets(b_name);
    }
    void showdetails()
    {
        cout<<"\n Book no.: "<<b_no;
        cout<<"\n Book name: ";
        puts(b_name);
    }
    int return_b_no() {return b_no;}
};
void insert()
{
    BOOK obj;
    obj.getdetails();
    ofstream ofile;
    ofile.open("BOOK.DAT",ios::app|ios::binary);
    ofile.write((char*)&obj,sizeof(obj));
    ofile.close();
    cout<<"\n Insert successful. Press any key to continue...";
    getch();
}
void display()
{
    BOOK obj;
    ifstream ifile;
    ifile.open("BOOK.DAT");
    while(ifile.read((char*)&obj,sizeof(obj)))
    {obj.showdetails();}
    ifile.close();
    cout<<"\n Press any key to continue...";
    getch();
}
void search()
{
    BOOK obj;
    int b_no,token=0;
    cout<<"\n Enter book no. to be searched: ";
    cin>>b_no;
    ifstream ifile;
    ifile.open("BOOK.DAT");
    while(ifile.read((char*)&obj,sizeof(obj)))
    {
        if(obj.return_b_no()==b_no)
        {
            cout<<"\n Record found!";
            token=1;
            obj.showdetails();
        }
    }
    ifile.close();
    if(token==0)
    cout<<"\n Record not found.";
    cout<<"\n Press any key to continue...";
    getch();
}
void count()
{
    BOOK obj;
    int count=0;
    ifstream ifile;
    ifile.open("BOOK.DAT");
    while(ifile.read((char*)&obj,sizeof(obj)))
    count++;
    ifile.close();
    cout<<"\n Number of records in the file: "<<count;
    cout<<"\n Press any key to continue...";
    getch();
}
void modify()
{
    BOOK obj;
    int b_no,token=0;
    int pos ;
    cout<<"\n Enter book no. to be modified: ";
    cin>>b_no;
    fstream file;
    file.open("BOOK.DAT",ios::binary|ios::in|ios::out);
    while(file.read((char*)&obj,sizeof(obj)))
    {
        pos=-1*sizeof(obj) ;
        if(obj.return_b_no()==b_no)
        {
            token=1;
            obj.showdetails();
            cout<<"\n Modify:\n";
            file.seekg(pos,ios::cur);
            obj.getdetails();
            file.write((char*)&obj,sizeof(obj));
            cout<<"\n Modify successful!";
        }
    }
    if(token==0)
    cout<<"\n Record not found.";
    cout<<"\n Press any key to continue...";
    file.close();
    getch();
}
void main()
{
    while(1)
    {
        clrscr();
        cout<<"\n\t\tMain Menu:-";
        cout<<"\n\n\t1.Insert";
        cout<<"\n\t2.Dispay";
        cout<<"\n\t3.Search";
        cout<<"\n\t4.Count";
        cout<<"\n\t5.Modify";
        cout<<"\n\t6.Exit";
        cout<<"\n\n\tEnter choice: ";
        int choice;
        cin>>choice;
        switch(choice)
        {
            case 1:
            insert();
            break;

            case 2:
            display();
            break;

            case 3:
            search();
            break;

            case 4:
            count();
            break;

            case 5:
            modify();
            break;

            case 6:
            exit(0);
        }
    }
}