Генератор и чекер тестовых данных

test_data.c

#include <stdio.h>
#include <stdlib.h>
#include <time.h>
#include <unistd.h>

#define MAX_INT 9999999


int randint(int from, int to) {
    return (from + rand() % to);
}

int build_data(FILE *file, unsigned long lines) {
    unsigned long i;
    for (i = 0; i < lines; i++) {
       fprintf(file, "%d\n", randint(0, MAX_INT));
    }
    return 1;
}

int check_data(FILE * file) {
    int parent_int = NULL;
    int current_int = NULL;
    while (fscanf(file, "%d\n", &current_int) != EOF) {
        fprintf(stdout, "%d\n", current_int);
        if ((parent_int == NULL)|(current_int >= parent_int)) {
            parent_int = current_int;
        } else {
           fprintf(stderr, "Not sortable\n");
            break;
        }
    }
}

int main (int argc, char **argv)
     {
       int check_data_mode = 0;
       char *filename = NULL;
       unsigned long lines = 1024;
       int index;
       int c;

       opterr = 0;

       while ((c = getopt(argc, argv, "cf:l:")) != -1)
         switch (c)
           {
           case 'c':
             check_data_mode = 1;
             break;
           case 'f':
             filename = optarg;
             break;
           case 'l':
             lines = strtol(optarg, NULL, 10);
             break;
           case '?':
             if ((optopt == 'f') | (optopt == 'l'))
               fprintf(stderr, "Option -%c requires an argument.\n", optopt);
             else if (isprint (optopt))
               fprintf(stderr, "Unknown option `-%c'.\n", optopt);
             else
               fprintf(stderr,
                        "Unknown option character `\\x%x'.\n",
                        optopt);
             return 1;
           default:
             abort();
           }

       printf ("check = %d, filename = %s, lines = %d\n",
               check_data_mode, filename, lines);

       for (index = optind; index < argc; index++)
         printf ("Non-option argument %s\n", argv[index]);

       FILE * file;
        if (filename == NULL)
        {
            if (check_data_mode) {
                file = stdin;
            } else {
                file = stdout;
            }
        } else {
            if (check_data_mode) {
                file = fopen(filename, "r");
            } else {
                file = fopen(filename, "w");
            }
        }

       if (check_data_mode) {
           check_data(file);
       } else {
           build_data(file, lines);
       }

       return 0;
 }