This is a classical problem, but I can not find a simple solution.

I have an input file like:

1 3 9 13 23 25 34 36 38 40 52 54 59 
2 3 9 14 23 26 34 36 39 40 52 55 59 63 67 76 85 86 90 93 99 108 114 
2 4 9 15 23 27 34 36 63 67 76 85 86 90 93 99 108 115 
1 25 34 36 38 41 52 54 59 63 67 76 85 86 90 93 98 107 113 
2 3 9 16 24 28 
2 3 10 14 23 26 34 36 39 41 52 55 59 63 67 76 

Lines of different number of integers separated by a space.

I would like to parse them in an array, and separate each line with a marker, let say -1.

The difficulty is that I must handle integers and line returns.

Here my existing code, it loops upon the scanf loop (because scanf can not begin at a given position).

#include <stdio.h>
#include <stdlib.h>
int main(int argc, char **argv) {

  if (argc != 4) {
    fprintf(stderr, "Usage: %s <data file> <nb transactions> <nb items>\n", argv[0]);
    return 1;
  }
  FILE * file;
  file = fopen (argv[1],"r");
  if (file==NULL) {
    fprintf(stderr, "Error: can not open %s\n", argv[1]);
    fclose(file);
    return 1;
  }
  int nb_trans = atoi(argv[2]);
  int nb_items = atoi(argv[3]);
  int *bdd = malloc(sizeof(int) * (nb_trans + nb_items));
  char line[1024];
  int i = 0;

  while ( fgets(line, 1024, file) ) {
    int item;
    while ( sscanf (line, "%d ", &item )){
      printf("%s %d %d\n", line, i, item);
      bdd[i++] = item;
    }
    bdd[i++] = -1;
  }

  for ( i = 0; i < nb_trans + nb_items; i++ ) {
    printf("%d ", bdd[i]);
  }
  printf("\n");
}