1.\" $NetBSD: bsearch.3,v 1.4 1995/12/28 08:52:09 thorpej Exp $ 2.\" 3.\" Copyright (c) 1990, 1991 The Regents of the University of California. 4.\" All rights reserved. 5.\" 6.\" This code is derived from software contributed to Berkeley by 7.\" the American National Standards Committee X3, on Information 8.\" Processing Systems. 9.\" 10.\" Redistribution and use in source and binary forms, with or without 11.\" modification, are permitted provided that the following conditions 12.\" are met: 13.\" 1. Redistributions of source code must retain the above copyright 14.\" notice, this list of conditions and the following disclaimer. 15.\" 2. Redistributions in binary form must reproduce the above copyright 16.\" notice, this list of conditions and the following disclaimer in the 17.\" documentation and/or other materials provided with the distribution. 18.\" 3. All advertising materials mentioning features or use of this software 19.\" must display the following acknowledgement: 20.\" This product includes software developed by the University of 21.\" California, Berkeley and its contributors. 22.\" 4. Neither the name of the University nor the names of its contributors 23.\" may be used to endorse or promote products derived from this software 24.\" without specific prior written permission. 25.\" 26.\" THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 27.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 28.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 29.\" ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 30.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 31.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 32.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 33.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 34.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 35.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 36.\" SUCH DAMAGE. 37.\" 38.\" from: @(#)bsearch.3 5.6 (Berkeley) 6/29/91 39.\" 40.Dd June 29, 1991 41.Dt BSEARCH 3 42.Os 43.Sh NAME 44.Nm bsearch 45.Nd binary search of a sorted table 46.Sh SYNOPSIS 47.Fd #include <stdlib.h> 48.Ft void * 49.Fn bsearch "const void *key" "const void *base" "size_t nmemb" "size_t size" "int (*compar) (const void *, const void *)" 50.Sh DESCRIPTION 51The 52.Fn bsearch 53function searches an array of 54.Fa nmemb 55objects, the initial member of which is 56pointed to by 57.Fa base , 58for a member that matches the object pointed to by 59.Fa key . 60The size of each member of the array is specified by 61.Fa size . 62.Pp 63The contents of the array should be in ascending sorted order according 64to the comparison function referenced by 65.Fa compar . 66The 67.Fa compar 68routine 69is expected to have two 70two arguments which point to the 71.Fa key 72object and to an array member, in that order, and should return an integer 73less than, equal to, or greater than zero if the 74.Fa key 75object is found, respectively, to be less than, to match, or be 76greater than the array member. 77.Sh RETURN VALUES 78The 79.Fn bsearch 80function returns a pointer to a matching member of the array, or a null 81pointer if no match is found. 82If two members compare as equal, which member is matched is unspecified. 83.Sh SEE ALSO 84.Xr db 3 , 85.Xr lsearch 3 , 86.Xr qsort 3 , 87.\" .Xr tsearch 3 88.Sh STANDARDS 89The 90.Fn bsearch 91function conforms to 92.St -ansiC . 93