#include <ctype.h>
#include <stdio.h>
 
#define MAX_TRANSACTIONS 10
 
struct items {
      double price;
      int quantity;
      double markup;
      double total_price;
      int total_sales;
};
 
void getnum(char *, const char *, void *);
 
struct items costs[MAX_TRANSACTIONS];
 
int trans;
 
double profit;
 
int main()
{
      struct items *p;
      char buffer[512];
      char prompt;
 
      do {
            fputs("\n\tBUSINESS CALC SOFTWARE\n\n\n\tHow many transactions do you want? : ", stdout);
            do {
                  getnum(buffer, "%d", &trans);
                  if(trans > MAX_TRANSACTIONS) {
                        fputs("\n\t\t(No transactions beyond 10)\n\n\tEnter transactions : ", stdout);
                        continue;
                  }
                  break;
            } while(1);
            profit = 0;
            for(p = costs; p < &costs[trans]; ++p) {
                  fputs("\n\n\tEnter item price : ", stdout);
                  getnum(buffer, "%lf", &p->price);
                  fputs("\n\tEnter item quantity : ", stdout);
                  getnum(buffer, "%d", &p->quantity);
                  fputs("\n\tEnter markup : ", stdout);
                  getnum(buffer, "%lf", &p->markup);
                  p->total_price = (p->price + p->markup) * p->quantity;
                  p->total_sales += p->total_price;
                  p->markup *= p->quantity;
                  printf("\n\n\tTotal item price : %.2lf\n\n\n\t", p->total_price);
                  profit += p->markup;
            }
            printf("\n\tTotal sales\t: %d", p->total_sales);
            printf("\n\tProfit\t\t: %.2lf\n\n", profit);
            fputs("\n\nDo you want another transaction? <y,n> ", stdout);
            getnum(buffer, "%c", &prompt);
            prompt = (isupper(prompt) ? tolower(prompt) : prompt);
      } while(prompt == 'y');
      return 0;
}
 
void getnum(char *buff, const char *format, void *ptr)
{
      fgets(buff, sizeof buff, stdin);
      sscanf(buff, format, ptr);
}