Need help in c++ filing. woking good in dev c++ but giving problem in MS visual 2010

[arman.ahmad]

This project is working good in dev c++.
In MS visual studio 2010 my modify function not working correctly. Problem is. when I modify last record using modify function record is modified as well as record at 2nd position appended at last. This problem is not occurred when programmed executed using dev c++. Please help me to figure out problem.

//***************************************************************
//                   HEADER FILE USED IN PROJECT
//***************************************************************
#include<iostream>
#include<conio.h>
#include<fstream>
#include<cstdlib>
#include<iomanip>
using namespace std;


//***************************************************************
//                   CLASS USED IN PROJECT
//****************************************************************
class item
{
    int ino;
    char name[50];
    float price,qty,dis;
public:
    /*item()
    {
        ino=0;
        price=0;
    }*/
    void add_item()
        {
            cout<<"\nPlease Enter the Item No. of the Item ";
            cin>>ino;
            cout<<"\n\nPlease Enter The Name of The Item ";
            cin.ignore();
            gets_s(name);
            cout<<"\nPlease Enter The Price of The Item ";
            cin>>price;
            cout<<"\nPlease Enter The Discount (%) ";
            cin>>dis;
        }

    void show_item()
    {
        cout<<"\nThe Item No. of The Item : "<<ino;
        cout<<"\nThe Name of The Item : ";
        puts(name);
        cout<<"The Price of The Item : "<<price;
        cout<<"\nDiscount (%) : "<<dis;
    }

    int  retino()
    {return ino;}

    float retprice()
    {return price;}

    char* retname()
    {return name;}

    float retdis()
    {return dis;}

};         //class ends here



//***************************************************************
//        global declaration for stream object, object
//****************************************************************
fstream fp;
item it;


//***************************************************************
//        function to write in file
//****************************************************************

void write_item()
   {
    fp.open("Shop.dat",ios::out|ios::app);
    it.add_item();
    fp.write((char*)&it,sizeof(item));
    fp.close();
    cout<<"\n\nThe Product Has Been Created ";
    _getch();
   }


//***************************************************************
//        function to read all records from file
//****************************************************************


void display_all()
{
    system("cls");
    cout<<"\n\n\n\t\tDISPLAY ALL RECORD !!!\n\n";
    fp.open("Shop.dat",ios::in);
    while(fp.read((char*)&it,sizeof(item)))
    {
     it.show_item();
     cout<<"\n\n====================================\n";
     _getch();
     }
    fp.close();
    _getch();
}


//***************************************************************
//        function to read specific record from file
//****************************************************************


void display_sp(int n)
{
    int flag=0;
    fp.open("Shop.dat",ios::in);
    while(fp.read((char*)&it,sizeof(item)))
    {
     if(it.retino()==n)
        {
         system("cls");
         it.show_item();
         flag=1;
        }
    }
    fp.close();
if(flag==0)
 cout<<"\n\nRecord not exist";
    _getch();
}


//****************************************************************
//        function to modify record of file
//****************************************************************


void modify_item()
{
    int no,found=0;
    system("cls");
    cout<<"\n\n\tTo Modify ";
    cout<<"\n\n\tPlease Enter The Product No. of The Product";
    cin>>no;
    fp.open("Shop.dat",ios::in|ios::out);
    while(((char*)&it,sizeof(item)) && found==0)
       {
        if(it.retino()==no)
           {
            it.show_item();
            cout<<"\nPlease Enter The New Details of Product"<<endl;
            it.add_item();
            long pos=sizeof(item);
            fp.seekp(-pos,ios::cur);
            fp.write((char*)&it,sizeof(item));
            cout<<"\n\n\t Record Updated";
            found=1;
           }
         }
    fp.close();
    if(found==0)
    cout<<"\n\n Record Not Found ";
    _getch();
}


//***************************************************************
//        function to delete record of file
//****************************************************************


void delete_item()
   {
    int no;
    system("cls");
    cout<<"\n\n\n\tDelete Record";
    cout<<"\n\nPlease Enter The Item no. of The Item You Want To Delete";
    cin>>no;
    fp.open("Shop.dat",ios::in|ios::out);
    fstream fp2;
    fp2.open("Temp.dat",ios::out);
    fp.seekg(0,ios::beg);
    while(fp.read((char*)&it,sizeof(item)))
    {
     if(it.retino()!=no)
        {
         fp2.write((char*)&it,sizeof(item));
         }
     }
    fp2.close();
    fp.close();
    remove("Shop.dat");
    rename("Temp.dat","Shop.dat");
    cout<<"\n\n\tRecord Deleted ..";
    _getch();
    }


//***************************************************************
//        function to display all products price list
//****************************************************************

    void menu()
    {
     system("cls");
     fp.open("Shop.dat",ios::in);
     if(!fp)
     {
       cout<<"ERROR!!! FILE COULD NOT BE OPEN\n\n\n Go To Admin Menu to create File";
       cout<<"\n\n\n Program is closing ....";
       _getch();
       exit(0);
     }

     cout<<"\n\n\t\tProduct MENU\n\n";
      cout<<"====================================================\n";
      cout<<"P.NO.\t\tNAME\t\t\tPRICE\n";
      cout<<"====================================================\n";

      while(fp.read((char*)&it,sizeof(item)))
     {
       cout<<it.retino()<<"\t\t"<<it.retname()<<"\t\t"<<it.retprice()<<endl;
    }
     fp.close();
}




//***************************************************************
//        function to place order and generating bill for Products
//****************************************************************

   void place_order()
   {
    int  order_arr[50],quan[50],c=0;
    float amt,damt,total=0;
    char ch='Y';
    menu();
    cout<<"\n============================";
    cout<<"\n    PLACE YOUR ORDER";
    cout<<"\n============================\n";
    do{
     cout<<"\n\nEnter The Item No. Of The Item : ";
     cin>>order_arr[c];
     cout<<"\nQuantity in number : ";
     cin>>quan[c];
     c++;
     cout<<"\nDo You Want To Order Another Product ? (y/n)";
     ch=_getche();
    }while(ch=='y' ||ch=='Y');
    cout<<"\n\nThank You For Placing The Order";
    _getch();
    system("cls");
      cout<<"\n\n********************************INVOICE************************\n";
      cout<<"\nPr No.\tPr Name\t\tQuantity \tPrice \tAmount \tDiscounted Amount\n";
      for(int x=0;x<=c;x++)
    {
         fp.open("Shop.dat",ios::in);
         fp.read((char*)&it,sizeof(item));
          while(!fp.eof())
            {
            if(it.retino()==order_arr[x])
                {
                 amt=it.retprice()*quan[x];
                 damt=amt-(amt*it.retdis()/100);
                 cout<<"\n"<<order_arr[x]<<"\t"<<it.retname()<<"\t"<<quan[x]<<"\t\t"<<it.retprice()<<"\t"<<amt<<"\t\t"<<damt;
                 total+=damt;
                }
            fp.read((char*)&it,sizeof(item));
            }

         fp.close();
     }
       cout<<"\n\n\t\t\t\t\tTOTAL = "<<total;
    _getch();
    }

//***************************************************************
//        INTRODUCTION FUNCTION
//****************************************************************

void intro()
{
 system("cls");
 //gotoxy(31,11);
 cout<<"SUPER MARKET";
 //gotoxy(35,14);
 cout<<"BILLING";
 //gotoxy(35,17);
 cout<<"PROJECT";
 cout<<"\n\nMADE BY : ABC";
 cout<<"\n\nSCHOOL : KFUEIT";
 _getch();

}




//***************************************************************
//        ADMINSTRATOR MENU FUNCTION
//****************************************************************
void admin_menu()
{
  system("cls");
  char ch2;
  cout<<"\n\n\n\tADMIN MENU";
  cout<<"\n\n\t1. ADD ITEM";
  cout<<"\n\n\t2. DISPLAY ALL ITEM";
  cout<<"\n\n\t3. QUERY ";
  cout<<"\n\n\t4. MODIFY ITEM";
  cout<<"\n\n\t5. DELETE ITEM";
  cout<<"\n\n\t6. VIEW ITEM MENU";
  cout<<"\n\n\t7. BACK TO MAIN MENU";
  cout<<"\n\n\tPlease Enter Your Choice (1-7) ";
  ch2=_getche();
  switch(ch2)
  {
    case '1': system("cls");
          write_item();
          break;
    case '2': display_all();
        break;
    case '3':
           int num;
           system("cls");
           cout<<"\n\n\tPlease Enter The Product No. ";
           cin>>num;
           display_sp(num);
           break;
      case '4': modify_item();break;
      case '5': delete_item();break;
      case '6': menu();
        _getch();
      case '7': break;
      default:cout<<"\a";
          admin_menu();
   }
}


//***************************************************************
//        THE MAIN FUNCTION OF PROGRAM
//****************************************************************


int main(void)
{
  char ch;
  intro();
  do
    {
      system("cls");
      cout<<"\n\n\n\tMAIN MENU";
      cout<<"\n\n\t1. CUSTOMER";
      cout<<"\n\n\t2. ADMINISTRATOR";
      cout<<"\n\n\t3. EXIT";
      cout<<"\n\n\tPlease Select Your Option (1-3) ";
      ch=_getche();
      switch(ch)
      {
         case '1': system("cls");
               place_order();
               //getch();
               break;
          case '2': admin_menu();
                break;
          case '3':
              exit(0);
          default :
              cout<<"\a";
    }
    }while(ch!='3');
    return 0;
}

//***************************************************************
//                END OF PROJECT
//***************************************************************

[2kaud]

while(((char*)&it,sizeof(item)) && found==0)

This looks wrong. With a comma separated statement, the expressions are evaluated left to right with the last expression executed being the value of the statement. In this case the address of it as a pointer to char is obtained and discarded. sizeof(item) is always greater than 0 so is treated as true as part of a logical and. So effectively this statement becomes

while (found == 0)

I think you mean

while (fp.read((char*)&it, sizeof(item)) && found == 0)

[Rabelo]

You are not reading every register to seek for the element to be modified. So the while is running loose till the end of the file. Do as you did on the delete function reading sequentially every element after the seek. the sequence is:

open the file;
found = false;
while not found
   read the element;                <<<======= MISSING
  is this the element I want? 
    if so 
      go back one register;
      save it
      found = true;
    else  Seek the next element;
end while;

if found = false
  print "element not found"
end if
...

[Rabelo]

Actually there is a litle bug on this algorythm that will break the program (or freeze the computer... )
if the element doses not exist the while won´t stop. So as this seems to be a school exercise I´ll let to you the solution...