manual/examples/search.c

   1 /* Searching and Sorting Example
   2    Copyright (C) 1991-2016 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU General Public License
   6    as published by the Free Software Foundation; either version 2
   7    of the License, or (at your option) any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, if not, see <http://www.gnu.org/licenses/>.
  16 */
  17
  18 #include <stdlib.h>
  19 #include <stdio.h>
  20 #include <string.h>
  21
  22 /* Define an array of critters to sort. */
  23
  24 struct critter
  25   {
  26     const char *name;
  27     const char *species;
  28   };
  29
  30 struct critter muppets[] =
  31   {
  32     {"Kermit", "frog"},
  33     {"Piggy", "pig"},
  34     {"Gonzo", "whatever"},
  35     {"Fozzie", "bear"},
  36     {"Sam", "eagle"},
  37     {"Robin", "frog"},
  38     {"Animal", "animal"},
  39     {"Camilla", "chicken"},
  40     {"Sweetums", "monster"},
  41     {"Dr. Strangepork", "pig"},
  42     {"Link Hogthrob", "pig"},
  43     {"Zoot", "human"},
  44     {"Dr. Bunsen Honeydew", "human"},
  45     {"Beaker", "human"},
  46     {"Swedish Chef", "human"}
  47   };
  48
  49 int count = sizeof (muppets) / sizeof (struct critter);
  50
  51
  52
  53 /* This is the comparison function used for sorting and searching. */
  54
  55 int
  56 critter_cmp (const void *v1, const void *v2)
  57 {
  58   const struct critter *c1 = v1;
  59   const struct critter *c2 = v2;
  60
  61   return strcmp (c1->name, c2->name);
  62 }
  63
  64
  65 /* Print information about a critter. */
  66
  67 void
  68 print_critter (const struct critter *c)
  69 {
  70   printf ("%s, the %s\n", c->name, c->species);
  71 }
  72
  73
  74 /*@group*/
  75 /* Do the lookup into the sorted array. */
  76
  77 void
  78 find_critter (const char *name)
  79 {
  80   struct critter target, *result;
  81   target.name = name;
  82   result = bsearch (&target, muppets, count, sizeof (struct critter),
  83                     critter_cmp);
  84   if (result)
  85     print_critter (result);
  86   else
  87     printf ("Couldn't find %s.\n", name);
  88 }
  89 /*@end group*/
  90
  91 /* Main program. */
  92
  93 int
  94 main (void)
  95 {
  96   int i;
  97
  98   for (i = 0; i < count; i++)
  99     print_critter (&muppets[i]);
 100   printf ("\n");
 101
 102   qsort (muppets, count, sizeof (struct critter), critter_cmp);
 103
 104   for (i = 0; i < count; i++)
 105     print_critter (&muppets[i]);
 106   printf ("\n");
 107
 108   find_critter ("Kermit");
 109   find_critter ("Gonzo");
 110   find_critter ("Janice");
 111
 112   return 0;
 113 }