489: Mainline

At this point, the analyze_trades program is reduced to displaying a straightforward report so as to provide a simpler base on which to build more C mechanisms. On the other hand, the trade structure is enriched to enable trade objects to retain an industry-encoding integer:

#include   
/* Define the trade apparatus */ 
struct trade {double price; int number; int industry;}; 
/* Define trade array */ 
struct trade *trade_pointers[100]; 
/* Define price-computing function */ 
double trade_price (struct trade *x) { 
  return x -> price * x -> number; 
} 
main ( ) { 
  /* Declare various variables */ 
  int limit, counter, number, industry; 
  double price; 
  /* Read trade information */ 
  for (limit = 0;  
       3 == scanf ("%i%lf%i", &industry, &price, &number); 
       ++limit) { 
    trade_pointers[limit]  
      = (struct trade*) malloc (sizeof (struct trade)); 
    trade_pointers[limit] -> price = price; 
    trade_pointers[limit] -> number = number; 
    trade_pointers[limit] -> industry = industry; 
  } 
  /* Display report */ 
  for (counter = 0; counter < limit; ++counter) 
    printf ("%i %f %i %f\n", 
             trade_pointers[counter] -> industry, 
             trade_pointers[counter] -> price, 
             trade_pointers[counter] -> number, 
             trade_price(trade_pointers[counter])); 
} 

As you can see, the purpose of this analyze_trades program is to regurgitate the information supplied for each trade, with the addition of a trade-price column.