#include <stdio.h> 
/* Define the trade structure */
struct trade {double price; int number;};
/* Define value-computing function */
double trade_price (struct trade *tptr) {
  return tptr -> price * tptr -> number;
}
/* Define trade array */
struct trade *trade_pointers[100];
main ( ) {
  /* Declare various variables */
  int limit, counter, number;
  double price, sum = 0;
  /* Define trade_source, a pointer to a file structure */
  FILE* trade_source;
  /* Define analysis_target, a pointer to a file structure */
  FILE* analysis_target;
  /* Prepare a file structure for reading */
  trade_source = fopen ("test.data", "r");
  /* Read numbers from the file and stuff them into array */
  for (limit = 0;
       2 == fscanf (trade_source, "%lf%i", &price, &number);
       ++limit) {
    trade_pointers[limit] 
      = (struct trade*) malloc (sizeof (struct trade));
    trade_pointers[limit] -> price = price;
    trade_pointers[limit] -> number = number;
  }
  /* Close source file /*
  fclose (trade_source);
  /* Find value of shares traded */
  for (counter = 0; counter < limit; ++counter)
    sum = sum + trade_price(trade_pointers[counter]);
  /* Prepare a file structure for writing*/
  analysis_target = fopen("test.result", "w");
  /* Write value of shares traded */
  fprintf (analysis_target,
           "The total value of the %i trades is %f.\n",
                                   limit,       sum);
  /* Close target file */
  fclose (analysis_target);
}