bsearch.3: Improve the example.
Submitted by: fernape MFC after: 1 week Differential revision: https://reviews.freebsd.org/D19902
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svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=350091
@ -32,7 +32,7 @@
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.\" @(#)bsearch.3 8.3 (Berkeley) 4/19/94
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.\" $FreeBSD$
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.\"
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.Dd May 15, 2019
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.Dd July 17, 2019
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.Dt BSEARCH 3
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.Os
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.Sh NAME
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@ -93,26 +93,29 @@ A sample program that searches people by age in a sorted array:
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#include <string.h>
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struct person {
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char name[5];
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const char *name;
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int age;
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};
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int
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compare(const void *key, const void *array_member)
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static int
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compare(const void *a, const void *b)
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{
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int age = (intptr_t) key;
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struct person person = *(struct person *) array_member;
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const int *age;
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const struct person *person;
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return (age - person.age);
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age = a;
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person = b;
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return (*age - person->age);
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}
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int
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main()
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main(void)
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{
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struct person *friend;
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int age;
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/* Sorted array */
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struct person friends[6] = {
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const struct person friends[] = {
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{ "paul", 22 },
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{ "anne", 25 },
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{ "fred", 25 },
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@ -120,22 +123,28 @@ main()
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{ "mark", 35 },
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{ "bill", 50 }
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};
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const size_t len = sizeof(friends) / sizeof(friends[0]);
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size_t array_size = sizeof(friends) / sizeof(struct person);
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friend = bsearch((void *)22, &friends, array_size, sizeof(struct person), compare);
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age = 22;
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friend = bsearch(&age, friends, len, sizeof(friends[0]), compare);
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assert(strcmp(friend->name, "paul") == 0);
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printf("name: %s\enage: %d\en", friend->name, friend->age);
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friend = bsearch((void *)25, &friends, array_size, sizeof(struct person), compare);
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assert(strcmp(friend->name, "fred") == 0 || strcmp(friend->name, "anne") == 0);
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age = 25;
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friend = bsearch(&age, friends, len, sizeof(friends[0]), compare);
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/*
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* For multiple elements with the same key, it is implementation
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* defined which will be returned
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*/
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assert(strcmp(friend->name, "fred") == 0 ||
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strcmp(friend->name, "anne") == 0);
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printf("name: %s\enage: %d\en", friend->name, friend->age);
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friend = bsearch((void *)30, &friends, array_size, sizeof(struct person), compare);
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age = 30;
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friend = bsearch(&age, friends, len, sizeof(friends[0]), compare);
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assert(friend == NULL);
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printf("friend aged 30 not found\en");
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return (EXIT_SUCCESS);
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}
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.Ed
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.Sh SEE ALSO
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