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annotate toys/other/factor.c @ 1626:89384d54d49a draft

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Teach factor to accept whitespace separated arguments (reported by Robert Thompson). (The diff looks bigger than it is because of reindenting.)
author Rob Landley <rob@landley.net>
date Wed, 24 Dec 2014 16:13:08 -0600
parents dd336488a69b
children 3ac823675413
Ignore whitespace changes - Everywhere: Within whitespace: At end of lines:
rev   line source
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1 /* factor.c - Factor integers
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2 *
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3 * Copyright 2014 Rob Landley <rob@landley.net>
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4 *
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5 * No standard, but it's in coreutils
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6
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7 USE_FACTOR(NEWTOY(factor, 0, TOYFLAG_USR|TOYFLAG_BIN))
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8
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9 config FACTOR
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10 bool "factor"
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11 default y
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12 help
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13 usage: factor NUMBER...
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14
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15 Factor integers.
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16 */
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17
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18 #include "toys.h"
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19
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20 static void factor(char *s)
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21 {
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22 long l, ll;
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23
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24 for (;;) {
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25 while(isspace(*s)) s++;
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26 if (!*s) return;
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27
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28 l = strtol(s, &s, 0);
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29 if (*s && !isspace(*s)) {
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30 error_msg("%s: not integer");
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31 return;
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32 }
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33
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34 printf("%ld:", l);
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35
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36 // Negative numbers have -1 as a factor
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37 if (l < 0) {
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38 printf(" -1");
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39 l *= -1;
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40 }
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41
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42 // Nothing below 4 has factors
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43 if (l < 4) {
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44 printf(" %ld\n", l);
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45 continue;
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46 }
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47
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48 // Special case factors of 2
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49 while (l && !(l&1)) {
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50 printf(" 2");
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51 l >>= 1;
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52 }
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53
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54 // test odd numbers.
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55 for (ll=3; ;ll += 2) {
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56 long lll = ll*ll;
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57
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58 if (lll>l || lll<ll) {
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59 if (l>1) printf(" %ld", l);
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60 break;
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61 }
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62 while (!(l%ll)) {
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63 printf(" %ld", ll);
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64 l /= ll;
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65 }
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66 }
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67 xputc('\n');
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68 }
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69 }
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70
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71 void factor_main(void)
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72 {
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73 if (toys.optc) {
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74 char **ss;
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75
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76 for (ss = toys.optargs; *ss; ss++) factor(*ss);
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77 } else for (;;) {
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78 char *s = 0;
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79 size_t len = 0;
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80
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81 if (-1 == getline(&s, &len, stdin)) break;
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82 factor(s);
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83 }
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84 }