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+'\" t
+.\" Copyright 1993 David Metcalfe (david@prism.demon.co.uk)
+.\"
+.\" SPDX-License-Identifier: Linux-man-pages-copyleft
+.\"
+.\" References consulted:
+.\" Linux libc source code
+.\" Lewine's _POSIX Programmer's Guide_ (O'Reilly & Associates, 1991)
+.\" 386BSD man pages
+.\" Modified Mon Mar 29 22:41:16 1993, David Metcalfe
+.\" Modified Sat Jul 24 21:35:16 1993, Rik Faith (faith@cs.unc.edu)
+.TH bsearch 3 2023-07-20 "Linux man-pages 6.05.01"
+.SH NAME
+bsearch \- binary search of a sorted array
+.SH LIBRARY
+Standard C library
+.RI ( libc ", " \-lc )
+.SH SYNOPSIS
+.nf
+.B #include <stdlib.h>
+.PP
+.BI "void *bsearch(const void " key [. size "], \
+const void " base [. size " * ." nmemb ],
+.BI " size_t " nmemb ", size_t " size ,
+.BI " int (*" compar ")(const void [." size "], \
+const void [." size ]));
+.fi
+.SH DESCRIPTION
+The
+.BR bsearch ()
+function searches an array of
+.I nmemb
+objects,
+the initial member of which is pointed to by
+.IR base ,
+for a member
+that matches the object pointed to by
+.IR key .
+The size of each member
+of the array is specified by
+.IR size .
+.PP
+The contents of the array should be in ascending sorted order according
+to the comparison function referenced by
+.IR compar .
+The
+.I compar
+routine is expected to have two arguments which point to the
+.I key
+object and to an array member, in that order, and should return an integer
+less than, equal to, or greater than zero if the
+.I key
+object is found,
+respectively, to be less than, to match, or be greater than the array
+member.
+.SH RETURN VALUE
+The
+.BR bsearch ()
+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.
+.SH ATTRIBUTES
+For an explanation of the terms used in this section, see
+.BR attributes (7).
+.TS
+allbox;
+lbx lb lb
+l l l.
+Interface Attribute Value
+T{
+.na
+.nh
+.BR bsearch ()
+T} Thread safety MT-Safe
+.TE
+.sp 1
+.SH STANDARDS
+C11, POSIX.1-2008.
+.SH HISTORY
+POSIX.1-2001, C89, C99, SVr4, 4.3BSD.
+.SH EXAMPLES
+The example below first sorts an array of structures using
+.BR qsort (3),
+then retrieves desired elements using
+.BR bsearch ().
+.PP
+.\" SRC BEGIN (bsearch.c)
+.EX
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+\&
+#define ARRAY_SIZE(arr) (sizeof((arr)) / sizeof((arr)[0]))
+\&
+struct mi {
+ int nr;
+ const char *name;
+};
+\&
+static struct mi 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" }
+};
+\&
+static int
+compmi(const void *m1, const void *m2)
+{
+ const struct mi *mi1 = m1;
+ const struct mi *mi2 = m2;
+\&
+ return strcmp(mi1\->name, mi2\->name);
+}
+\&
+int
+main(int argc, char *argv[])
+{
+ qsort(months, ARRAY_SIZE(months), sizeof(months[0]), compmi);
+ for (size_t i = 1; i < argc; i++) {
+ struct mi key;
+ struct mi *res;
+\&
+ key.name = argv[i];
+ res = bsearch(&key, months, ARRAY_SIZE(months),
+ sizeof(months[0]), compmi);
+ if (res == NULL)
+ printf("\[aq]%s\[aq]: unknown month\en", argv[i]);
+ else
+ printf("%s: month #%d\en", res\->name, res\->nr);
+ }
+ exit(EXIT_SUCCESS);
+}
+.EE
+.\" SRC END
+.SH SEE ALSO
+.BR hsearch (3),
+.BR lsearch (3),
+.BR qsort (3),
+.BR tsearch (3)