cnpj.c

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <time.h>
#include "brtools.h"

static int A[12] = {5,4,3,2,9,8,7,6,5,4,3,2};
static int B[13] = {6,5,4,3,2,9,8,7,6,5,4,3,2};

static char numbers[10] = "0123456789";

static void to_string(const int* const buffer, char* dest, int length) {
  for (int c = 0; c < length; c++) {
    dest[c] = numbers[buffer[c]];
  }
}

int main(void) {
  (void)srandom(time(NULL));

  int* buffer = (int*)malloc(sizeof(int) * 16);
  if (!buffer)
    return 1;

  memset(buffer, 0, sizeof(int) * 16);

  for (int c = 0; c < 12; c++) {
    buffer[c] = (int)((random() * 9 / RAND_MAX));
  }

  int calc = 0;
  calc = calculate(buffer, A, 14);
  buffer[12] = calc;

  calc = calculate(buffer, B, 14);
  buffer[13] = calc;
  buffer[14] = 0;

  char* as_str = (char*)malloc(sizeof(char) * 16);
  if (!as_str) {
    free(buffer);
    return 1;
  }

  (void)memset(as_str, 0, sizeof(char) * 16);
  to_string(buffer, as_str, 14);
  printf("%s\n", as_str);

  free(buffer);
  free(as_str);

  return 0;
}