problem with inventory program

this program uses fstream

data file
format:
productid productname quantity purchasedate

Code:

 10212 Nescafe 20 10/12/05
13114 Pepsi 11 10/27/05
11234 Nescafe 14 11/01/05
10212 Nescafe 30 11/05/05
10212 Pepsi 32 11/15/05
10212 Nescafe 45 11/21/05
13114 Nescafe 26 12/01/05
18456 Pepsi 23 12/20/05
12223 Frito -2 09/14/05
12223 Frito 20 9/14/05
12223 Frito 20 13/21/05
10212 Pepsi 32 01/15/06

code

Code:

#include <iostream>
#include <fstream>
#include <string>

#define SIZE 100
using namespace std;

class store
{
      public:
             int custnum;
             string product;
             int quantity;
             string month;
             string day;
             string year;
};

store STORE1[SIZE];

int num_lines(char name[]) // this function counts the number of lines in file
{
char templine[100];
int line=0;
    fstream in_file(name,ios::in);
    if(!in_file)
    {
      cout << "error opening file";
      exit(1);
    }
    while (!in_file.eof()){
      in_file.getline(templine,100);
      line++;
      
                }
                in_file.close();
                return line;

}

void period()
{

}

void all()
{
     cout << "THIS IS A TEST TO SEE IF THE FUNCTION WORKS" << endl;
}

void menu()
{
     int option,line,custnum,quantity,tmp,y=0;  
     string product;
     char month[80], day[80], year[80];
     char name[20];
     cout << "Enter name of file to load:";
     cin >> name;
     line = num_lines(name);

     fstream in_file(name,ios::in);
     if(!in_file)
     {
         cout << "error opening file";
         exit(1);
     }
     for(int x=0;x<line;x++)
     {
             in_file >> custnum;
             in_file >> product;
             in_file >> quantity;
             in_file.getline(month,100,'/');
             in_file.getline(day,100,'/');
             in_file >> year;
             in_file.ignore(80,'\n'); 
             tmp = atoi(month);
             if(tmp > 12 || tmp < 1 || strlen(month) < 3 || quantity <0)
                      cout << "Line " << x << " has invalid format" << endl; 
             else {

                  STORE1[y].custnum = custnum;
                  STORE1[y].product = product;
                  STORE1[y].quantity = quantity;
                  STORE1[y].month = month;
                  STORE1[y].day = day;
                  STORE1[y].year = year;
                  y++;                
          
             }
      }  



     in_file.close(); 
     cout << "The month is " << STORE1[0].month << endl;

     
     do {
   
     cout << "Please select a menu option:" << endl;
     cout << "1)Product sales in a given period" << endl;
     cout << "2)Information about all sales" << endl;
     cout << "3)Quit the program" << endl;
     cout << "Option (1,2,3):";
     cin >> option;
   
     switch(option) {
     case 1: 
          period();
          break;
     case 2:
          all();
          break;
          }
   
     } while(option!=3);
}

int main()
{
    menu();
    system("PAUSE");
    return 0;   
}

my plan for option one is for the user to enter the product name and specify a time period...
for example:

Code:

Please select a menu option: 
1)Product sales in a given period
2)Information about all sales
3)Quit the program
Option (1,2,3): 1

Enter a product name: Nescafe
Enter a starting date: 10/01/05
Enter an ending date: 12/01/05

it would show

Code:

Product: Nescafe
Total sales:	  135
First time sales: 60
Other sales:  75

i have a problem finding which are the first time purchases within the user entered time period... how would i do this?

Hi,

i have a problem finding which are the first time purchases within the user entered time period... how would i do this?

You need to compare all the date strings of the form 10/12/05. To compare dates, you first need to compare the year. If one is less than the other, then you know which date is earlier. If the years are the same, then you need to compare the months. If the months are the same then you need to compare the days.

So, the first step is to separate the string into the three pieces. You can use <string> functions like substr() to do that. The 3 pieces will be strings themselves. You can actually just compare the string pieces without converting them to numbers. The <string> class has comparison operators, ==, <, and > that compare strings by looking at the ascii character codes of each character in a string. The codes for numerical characters are in the same order as the corresponding integers, so there is no need to convert the strings to numbers to compare them. For instance, the string "12" is greater than the string "07", just as the integer 12 is greater than the integer 7. The <string> comparison operators start at the first characters in the strings and compare them, if the first characters are equal, then the 2nd characters are compared, and so on.

How Can We Make A C++ Program That Uses Function That Will Help Cashier To Solve/compute Total Sales.
You Will Use Code Instead Of Product Names.