{"id":7130,"date":"2022-12-20T19:35:34","date_gmt":"2022-12-20T22:35:34","guid":{"rendered":"http:\/\/lode.uno\/linux-man\/index.php\/2022\/12\/20\/bsearch-man3\/"},"modified":"2022-12-20T19:35:34","modified_gmt":"2022-12-20T22:35:34","slug":"bsearch-man3","status":"publish","type":"post","link":"https:\/\/lode.uno\/linux-man\/2022\/12\/20\/bsearch-man3\/","title":{"rendered":"BSEARCH (man3)"},"content":{"rendered":"

BSEARCH<\/h1>\n

NAME<\/a>
SYNOPSIS<\/a>
DESCRIPTION<\/a>
RETURN VALUE<\/a>
ATTRIBUTES<\/a>
CONFORMING TO<\/a>
EXAMPLES<\/a>
SEE ALSO<\/a>
COLOPHON<\/a> <\/p>\n

\n

NAME <\/a> <\/h2>\n

bsearch \u2212 binary search of a sorted array<\/p>\n

SYNOPSIS <\/a> <\/h2>\n

#include <\/b><\/p>\n

void *bsearch(const void *<\/b>key<\/i>, const void *<\/b>base<\/i>,
size_t<\/b> nmemb<\/i>, size_t<\/b> size<\/i>,
int (*<\/b>compar<\/i>)(const void *, const void *));<\/b><\/p>\n

DESCRIPTION <\/a> <\/h2>\n

The bsearch<\/b>() function searches an array of nmemb<\/i> objects, the initial member of which is pointed to by base<\/i>, for a member that matches the object pointed to by key<\/i>. The size of each member of the array is specified by size<\/i>.<\/p>\n

The contents of the array should be in ascending sorted order according to the comparison function referenced by compar<\/i>. The compar<\/i> routine is expected to have two arguments which point to the key<\/i> object and to an array member, in that order, and should return an integer less than, equal to, or greater than zero if the key<\/i> object is found, respectively, to be less than, to match, or be greater than the array member.<\/p>\n

RETURN VALUE <\/a> <\/h2>\n

The bsearch<\/b>() function returns a pointer to a matching member of the array, or NULL if no match is found. If there are multiple elements that match the key, the element returned is unspecified.<\/p>\n

ATTRIBUTES <\/a> <\/h2>\n

For an explanation of the terms used in this section, see attributes<\/b>(7).<\/p>\n\n\n\n
<\/td>\n <\/td>\n <\/td>\n<\/td>\n<\/td>\n <\/td>\n<\/tr>\n
<\/td>\n<\/td>\n <\/td>\n<\/td>\n<\/td>\n <\/td>\n<\/tr>\n<\/table>\n

\"Image<\/p>\n

CONFORMING TO <\/a> <\/h2>\n

POSIX.1-2001, POSIX.1-2008, C89, C99, SVr4, 4.3BSD.<\/p>\n

EXAMPLES <\/a> <\/h2>\n

The example below first sorts an array of structures using qsort<\/b>(3), then retrieves desired elements using bsearch<\/b>().<\/p>\n

#include
#include
#include <\/p>\n

struct mi {
int nr;
char *name;
} months[] = {
{ 1, “jan” }, { 2, “feb” }, { 3, “mar” }, { 4, “apr” },
{ 5, “may” }, { 6, “jun” }, { 7, “jul” }, { 8, “aug” },
{ 9, “sep” }, {10, “oct” }, {11, “nov” }, {12, “dec” }
};<\/p>\n

#define nr_of_months (sizeof(months)\/sizeof(months[0]))<\/p>\n

static int
compmi(const void *m1, const void *m2)
{
const struct mi *mi1 = m1;
const struct mi *mi2 = m2;
return strcmp(mi1\u2212>name, mi2\u2212>name);
}<\/p>\n

int
main(int argc, char **argv)
{
qsort(months, nr_of_months, sizeof(months[0]), compmi);
for (int i = 1; i < argc; i++) {
struct mi key;
struct mi *res;<\/p>\n

key.name = argv[i];
res = bsearch(&key, months, nr_of_months,
sizeof(months[0]), compmi);
if (res == NULL)
printf(“‘%s’: unknown monthn”, argv[i]);
else
printf(“%s: month #%dn”, res\u2212>name, res\u2212>nr);
}
exit(EXIT_SUCCESS);
}<\/p>\n

SEE ALSO <\/a> <\/h2>\n

hsearch<\/b>(3), lsearch<\/b>(3), qsort<\/b>(3), tsearch<\/b>(3)<\/p>\n

COLOPHON <\/a> <\/h2>\n

This page is part of release 5.10 of the Linux man-pages<\/i> project. A description of the project, information about reporting bugs, and the latest version of this page, can be found at https:\/\/www.kernel.org\/doc\/man\u2212pages\/.<\/p>\n

\n","protected":false},"excerpt":{"rendered":"

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