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author | Benedict Reuschling <bcr@FreeBSD.org> | 2019-05-15 15:54:27 +0000 |
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committer | Benedict Reuschling <bcr@FreeBSD.org> | 2019-05-15 15:54:27 +0000 |
commit | 15c9c06e6a25a84cffdf0e2c6460119b239dbe55 (patch) | |
tree | 67070d55b6f334e5e42636c2b3889075b8c0e526 /lib | |
parent | 6aa63d8dbe8db841d2344092e2e90323b7f8b860 (diff) | |
download | src-15c9c06e6a25a84cffdf0e2c6460119b239dbe55.tar.gz src-15c9c06e6a25a84cffdf0e2c6460119b239dbe55.zip |
Add small EXAMPLE section to bsearch.3.
Submitted by: fernape (via Phabricator)
Reviewed by: bcr, jilles, dab
Approved by: bcr (man pages), jilles (src)
MFC after: 3 days
Differential Revision: https://reviews.freebsd.org/D19902
Notes
Notes:
svn path=/head/; revision=347617
Diffstat (limited to 'lib')
-rw-r--r-- | lib/libc/stdlib/bsearch.3 | 57 |
1 files changed, 56 insertions, 1 deletions
diff --git a/lib/libc/stdlib/bsearch.3 b/lib/libc/stdlib/bsearch.3 index 2fdf2c4842c0..87f4cc862204 100644 --- a/lib/libc/stdlib/bsearch.3 +++ b/lib/libc/stdlib/bsearch.3 @@ -32,7 +32,7 @@ .\" @(#)bsearch.3 8.3 (Berkeley) 4/19/94 .\" $FreeBSD$ .\" -.Dd February 22, 2013 +.Dd May 15, 2019 .Dt BSEARCH 3 .Os .Sh NAME @@ -83,6 +83,61 @@ The function returns a pointer to a matching member of the array, or a null pointer if no match is found. If two members compare as equal, which member is matched is unspecified. +.Sh EXAMPLES +A sample program that searches people by age in a sorted array: +.Bd -literal +#include <assert.h> +#include <stdint.h> +#include <stdio.h> +#include <stdlib.h> +#include <string.h> + +struct person { + char name[5]; + int age; +}; + +int +compare(const void *key, const void *array_member) +{ + int age = (intptr_t) key; + struct person person = *(struct person *) array_member; + + return (age - person.age); +} + +int +main() +{ + struct person *friend; + + /* Sorted array */ + struct person friends[6] = { + { "paul", 22 }, + { "anne", 25 }, + { "fred", 25 }, + { "mary", 27 }, + { "mark", 35 }, + { "bill", 50 } + }; + + size_t array_size = sizeof(friends) / sizeof(struct person); + + friend = bsearch((void *)22, &friends, array_size, sizeof(struct person), compare); + assert(strcmp(friend->name, "paul") == 0); + printf("name: %s\enage: %d\en", friend->name, friend->age); + + friend = bsearch((void *)25, &friends, array_size, sizeof(struct person), compare); + assert(strcmp(friend->name, "fred") == 0 || strcmp(friend->name, "anne") == 0); + printf("name: %s\enage: %d\en", friend->name, friend->age); + + friend = bsearch((void *)30, &friends, array_size, sizeof(struct person), compare); + assert(friend == NULL); + printf("friend aged 30 not found\en"); + + return (EXIT_SUCCESS); +} +.Ed .Sh SEE ALSO .Xr db 3 , .Xr lsearch 3 , |