1.\" Copyright (c) 1990, 1991, 1993, 1994 2.\" The Regents of the University of California. All rights reserved. 3.\" 4.\" This code is derived from software contributed to Berkeley by 5.\" the American National Standards Committee X3, on Information 6.\" Processing Systems. 7.\" 8.\" Redistribution and use in source and binary forms, with or without 9.\" modification, are permitted provided that the following conditions 10.\" are met: 11.\" 1. Redistributions of source code must retain the above copyright 12.\" notice, this list of conditions and the following disclaimer. 13.\" 2. Redistributions in binary form must reproduce the above copyright 14.\" notice, this list of conditions and the following disclaimer in the 15.\" documentation and/or other materials provided with the distribution. 16.\" 3. Neither the name of the University nor the names of its contributors 17.\" may be used to endorse or promote products derived from this software 18.\" without specific prior written permission. 19.\" 20.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 21.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 22.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 23.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 24.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 25.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 26.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 27.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 28.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 29.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 30.\" SUCH DAMAGE. 31.\" 32.\" @(#)bsearch.3 8.3 (Berkeley) 4/19/94 33.\" $FreeBSD: src/lib/libc/stdlib/bsearch.3,v 1.9 2007/01/09 00:28:09 imp Exp $ 34.\" $DragonFly: src/lib/libc/stdlib/bsearch.3,v 1.2 2003/06/17 04:26:46 dillon Exp $ 35.\" 36.Dd April 19, 1994 37.Dt BSEARCH 3 38.Os 39.Sh NAME 40.Nm bsearch 41.Nd binary search of a sorted table 42.Sh LIBRARY 43.Lb libc 44.Sh SYNOPSIS 45.In stdlib.h 46.Ft void * 47.Fn bsearch "const void *key" "const void *base" "size_t nmemb" "size_t size" "int (*compar) (const void *, const void *)" 48.Sh DESCRIPTION 49The 50.Fn bsearch 51function searches an array of 52.Fa nmemb 53objects, the initial member of which is 54pointed to by 55.Fa base , 56for a member that matches the object pointed to by 57.Fa key . 58The size of each member of the array is specified by 59.Fa size . 60.Pp 61The contents of the array should be in ascending sorted order according 62to the comparison function referenced by 63.Fa compar . 64The 65.Fa compar 66routine 67is expected to have 68two arguments which point to the 69.Fa key 70object and to an array member, in that order, and should return an integer 71less than, equal to, or greater than zero if the 72.Fa key 73object is found, respectively, to be less than, to match, or be 74greater than the array member. 75.Sh RETURN VALUES 76The 77.Fn bsearch 78function returns a pointer to a matching member of the array, or a null 79pointer if no match is found. 80If two members compare as equal, which member is matched is unspecified. 81.Sh SEE ALSO 82.Xr db 3 , 83.Xr lsearch 3 , 84.Xr qsort 3 85.\" .Xr tsearch 3 86.Sh STANDARDS 87The 88.Fn bsearch 89function conforms to 90.St -isoC . 91