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git-svn-id: file:///srv/svn/joey/bsdgames-trunk@5086 a4a2c43b-8ac3-0310-8836-e0e880c912e2
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joey
212
factor/factor.c
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212
factor/factor.c
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/* $NetBSD: factor.c,v 1.8 1998/09/13 15:27:27 hubertf Exp $ */
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/*
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* Copyright (c) 1989, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Landon Curt Noll.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#ifndef lint
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__COPYRIGHT("@(#) Copyright (c) 1989, 1993\n\
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The Regents of the University of California. All rights reserved.\n");
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#endif /* not lint */
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#ifndef lint
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#if 0
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static char sccsid[] = "@(#)factor.c 8.4 (Berkeley) 5/4/95";
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#else
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__RCSID("$NetBSD: factor.c,v 1.8 1998/09/13 15:27:27 hubertf Exp $");
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#endif
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#endif /* not lint */
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/*
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* factor - factor a number into primes
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*
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* By: Landon Curt Noll chongo@toad.com, ...!{sun,tolsoft}!hoptoad!chongo
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*
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* chongo <for a good prime call: 391581 * 2^216193 - 1> /\oo/\
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*
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* usage:
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* factor [number] ...
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*
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* The form of the output is:
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*
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* number: factor1 factor1 factor2 factor3 factor3 factor3 ...
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*
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* where factor1 < factor2 < factor3 < ...
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*
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* If no args are given, the list of numbers are read from stdin.
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*/
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#include <err.h>
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#include <ctype.h>
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#include <errno.h>
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#include <limits.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <unistd.h>
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#include "primes.h"
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/*
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* prime[i] is the (i-1)th prime.
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*
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* We are able to sieve 2^32-1 because this byte table yields all primes
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* up to 65537 and 65537^2 > 2^32-1.
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*/
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extern const ubig prime[];
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extern const ubig *pr_limit; /* largest prime in the prime array */
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int main __P((int, char *[]));
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void pr_fact __P((ubig)); /* print factors of a value */
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void usage __P((void)) __attribute__((__noreturn__));
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int
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main(argc, argv)
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int argc;
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char *argv[];
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{
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ubig val;
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int ch;
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char *p, buf[100]; /* > max number of digits. */
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/* Revoke setgid privileges */
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setregid(getgid(), getgid());
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while ((ch = getopt(argc, argv, "")) != -1)
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switch (ch) {
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case '?':
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default:
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usage();
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}
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argc -= optind;
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argv += optind;
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/* No args supplied, read numbers from stdin. */
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if (argc == 0)
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for (;;) {
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if (fgets(buf, sizeof(buf), stdin) == NULL) {
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if (ferror(stdin))
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err(1, "stdin");
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exit (0);
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}
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for (p = buf; isblank(*p); ++p);
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if (*p == '\n' || *p == '\0')
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continue;
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if (*p == '-')
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errx(1, "negative numbers aren't permitted.");
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errno = 0;
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val = strtoul(buf, &p, 10);
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if (errno)
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err(1, "%s", buf);
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if (*p != '\n')
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errx(1, "%s: illegal numeric format.", buf);
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pr_fact(val);
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}
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/* Factor the arguments. */
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else
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for (; *argv != NULL; ++argv) {
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if (argv[0][0] == '-')
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errx(1, "negative numbers aren't permitted.");
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errno = 0;
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val = strtoul(argv[0], &p, 10);
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if (errno)
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err(1, "%s", argv[0]);
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if (*p != '\0')
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errx(1, "%s: illegal numeric format.", argv[0]);
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pr_fact(val);
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}
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exit(0);
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}
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/*
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* pr_fact - print the factors of a number
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*
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* If the number is 0 or 1, then print the number and return.
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* If the number is < 0, print -1, negate the number and continue
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* processing.
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*
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* Print the factors of the number, from the lowest to the highest.
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* A factor will be printed numtiple times if it divides the value
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* multiple times.
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*
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* Factors are printed with leading tabs.
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*/
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void
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pr_fact(val)
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ubig val; /* Factor this value. */
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{
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const ubig *fact; /* The factor found. */
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/* Firewall - catch 0 and 1. */
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if (val == 0) /* Historical practice; 0 just exits. */
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exit(0);
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if (val == 1) {
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(void)printf("1: 1\n");
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return;
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}
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/* Factor value. */
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(void)printf("%lu:", val);
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for (fact = &prime[0]; val > 1; ++fact) {
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/* Look for the smallest factor. */
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do {
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if (val % (long)*fact == 0)
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break;
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} while (++fact <= pr_limit);
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/* Watch for primes larger than the table. */
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if (fact > pr_limit) {
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(void)printf(" %lu", val);
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break;
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}
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/* Divide factor out until none are left. */
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do {
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(void)printf(" %lu", *fact);
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val /= (long)*fact;
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} while ((val % (long)*fact) == 0);
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/* Let the user know we're doing something. */
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(void)fflush(stdout);
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}
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(void)putchar('\n');
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}
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void
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usage()
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{
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(void)fprintf(stderr, "usage: factor [value ...]\n");
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exit (0);
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}
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