/* a simple example of using fread and fwrite
 * to read and write an array of structures
 */
#include <stdio.h>
//#include <unistd.h>
//#include <fcntl.h>
#include <assert.h>

#define NELEM 3

int main(void)
{
   FILE *fp;

   // the product structure
   struct product {
      int cat_num;
      float cost;
   };
   typedef struct product product;
  
   product productarr[NELEM] = {{2,20.1},{4,40.1},{6,60.1}};
   product one_product, *product_ptr = &one_product;

   int i, irc; // return code

   fp = fopen("c11-struct-file","w+");
   assert(fp != NULL);

   // write the entire array into the file pointed to by fp
   irc = fwrite(productarr, sizeof(product), NELEM, fp);
   printf(" fwrite return code = %d\n", irc);

   // prpare for reading from the beginning of the file
   rewind(fp);
  
   // read from the file one product at a time
   for (i=0; i<NELEM; i++) {
     fread(product_ptr, sizeof(product), 1, fp);
     printf(" product %d) cat_num=%d, cost=%f\n",
            i, 
            product_ptr->cat_num,
            product_ptr->cost);
   }

   return 0;
}