release/src-rt-6.x.4708/router/gmp/demos/isprime.c

   1 /* Classify numbers as probable primes, primes or composites.
   2    With -q return true if the following argument is a (probable) prime.
   3
   4 Copyright 1999, 2000, 2002, 2005, 2012 Free Software Foundation, Inc.
   5
   6 This program is free software; you can redistribute it and/or modify it under
   7 the terms of the GNU General Public License as published by the Free Software
   8 Foundation; either version 3 of the License, or (at your option) any later
   9 version.
  10
  11 This program is distributed in the hope that it will be useful, but WITHOUT ANY
  12 WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A
  13 PARTICULAR PURPOSE.  See the GNU General Public License for more details.
  14
  15 You should have received a copy of the GNU General Public License along with
  16 this program.  If not, see https://www.gnu.org/licenses/.  */
  17
  18 #include <stdlib.h>
  19 #include <string.h>
  20 #include <stdio.h>
  21 #include "gmp.h"
  22
  23 char *progname;
  24
  25 void
  26 print_usage_and_exit ()
  27 {
  28   fprintf (stderr, "usage: %s -q nnn\n", progname);
  29   fprintf (stderr, "usage: %s nnn ...\n", progname);
  30   exit (-1);
  31 }
  32
  33 int
  34 main (int argc, char **argv)
  35 {
  36   mpz_t n;
  37   int i;
  38
  39   progname = argv[0];
  40
  41   if (argc < 2)
  42     print_usage_and_exit ();
  43
  44   mpz_init (n);
  45
  46   if (argc == 3 && strcmp (argv[1], "-q") == 0)
  47     {
  48       if (mpz_set_str (n, argv[2], 0) != 0)
  49         print_usage_and_exit ();
  50       exit (mpz_probab_prime_p (n, 25) == 0);
  51     }
  52
  53   for (i = 1; i < argc; i++)
  54     {
  55       int class;
  56       if (mpz_set_str (n, argv[i], 0) != 0)
  57         print_usage_and_exit ();
  58       class = mpz_probab_prime_p (n, 25);
  59       mpz_out_str (stdout, 10, n);
  60       if (class == 0)
  61         puts (" is composite");
  62       else if (class == 1)
  63         puts (" is a probable prime");
  64       else /* class == 2 */
  65         puts (" is a prime");
  66     }
  67   exit (0);
  68 }