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[dragonfly.git] / lib / libc / stdlib / bsearch.3
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36.\" @(#)bsearch.3 8.3 (Berkeley) 4/19/94
37.\" $FreeBSD: src/lib/libc/stdlib/bsearch.3,v 1.4.2.4 2001/12/14 18:33:58 ru Exp $
38.\"
39.Dd April 19, 1994
40.Dt BSEARCH 3
41.Os
42.Sh NAME
43.Nm bsearch
44.Nd binary search of a sorted table
45.Sh LIBRARY
46.Lb libc
47.Sh SYNOPSIS
48.In stdlib.h
49.Ft void *
50.Fn bsearch "const void *key" "const void *base" "size_t nmemb" "size_t size" "int (*compar) (const void *, const void *)"
51.Sh DESCRIPTION
52The
53.Fn bsearch
54function searches an array of
55.Fa nmemb
56objects, the initial member of which is
57pointed to by
58.Fa base ,
59for a member that matches the object pointed to by
60.Fa key .
61The size of each member of the array is specified by
62.Fa size .
63.Pp
64The contents of the array should be in ascending sorted order according
65to the comparison function referenced by
66.Fa compar .
67The
68.Fa compar
69routine
70is expected to have
71two arguments which point to the
72.Fa key
73object and to an array member, in that order, and should return an integer
74less than, equal to, or greater than zero if the
75.Fa key
76object is found, respectively, to be less than, to match, or be
77greater than the array member.
78.Sh RETURN VALUES
79The
80.Fn bsearch
81function returns a pointer to a matching member of the array, or a null
82pointer if no match is found.
83If two members compare as equal, which member is matched is unspecified.
84.Sh SEE ALSO
85.Xr db 3 ,
86.Xr lsearch 3 ,
87.Xr qsort 3
88.\" .Xr tsearch 3
89.Sh STANDARDS
90The
91.Fn bsearch
92function conforms to
93.St -isoC .