.\" Copyright (c) 1990, 1991, 1993, 1994 .\" The Regents of the University of California. All rights reserved. .\" .\" This code is derived from software contributed to Berkeley by .\" the American National Standards Committee X3, on Information .\" Processing Systems. .\" .\" Redistribution and use in source and binary forms, with or without .\" modification, are permitted provided that the following conditions .\" are met: .\" 1. Redistributions of source code must retain the above copyright .\" notice, this list of conditions and the following disclaimer. .\" 2. Redistributions in binary form must reproduce the above copyright .\" notice, this list of conditions and the following disclaimer in the .\" documentation and/or other materials provided with the distribution. .\" 4. Neither the name of the University nor the names of its contributors .\" may be used to endorse or promote products derived from this software .\" without specific prior written permission. .\" .\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE .\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" .\" @(#)bsearch.3 8.3 (Berkeley) 4/19/94 .\" $FreeBSD: src/lib/libc/stdlib/bsearch.3,v 1.9 2007/01/09 00:28:09 imp Exp $ .\" .Dd May 20, 2008 .Dt BSEARCH 3 .Os .Sh NAME #ifdef UNIFDEF_BLOCKS .Nm bsearch , .Nm bsearch_b #else .Nm bsearch #endif .Nd binary search of a sorted table .Sh SYNOPSIS .In stdlib.h .Ft void * .Fn bsearch "const void *key" "const void *base" "size_t nel" "size_t width" "int (*compar) (const void *, const void *)" #ifdef UNIFDEF_BLOCKS .Ft void * .Fn bsearch_b "const void *key" "const void *base" "size_t nel" "size_t width" "int (^compar) (const void *, const void *)" #endif .Sh DESCRIPTION The .Fn bsearch function searches an array of .Fa nel objects, the initial member of which is pointed to by .Fa base , for a member that matches the object pointed to by .Fa key . The size (in bytes) of each member of the array is specified by .Fa width . .Pp The contents of the array should be in ascending sorted order according to the comparison function referenced by .Fa compar . The .Fa compar routine is expected to have two arguments which point to the .Fa key object and to an array member, in that order. It should return an integer which is less than, equal to, or greater than zero if the .Fa key object is found, respectively, to be less than, to match, or be greater than the array member. #ifdef UNIFDEF_BLOCKS .Pp The .Fn bsearch_b function is like .Fn bsearch except the callback .Fa compar is a block pointer instead of a function pointer. #endif .Sh RETURN VALUES The .Fn bsearch #ifdef UNIFDEF_BLOCKS and .Fn bsearch_b functions #else function #endif 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 SEE ALSO .Xr db 3 , .Xr lsearch 3 , .Xr qsort 3 .\" .Xr tsearch 3 .Sh STANDARDS The .Fn bsearch function conforms to .St -isoC .