[apple/libc.git] / stdlib / lsearch.3

.\"
.\" Initial implementation:
.\" Copyright (c) 2002 Robert Drehmel
.\" All rights reserved.
.\"
.\" As long as the above copyright statement and this notice remain
.\" unchanged, you can do what ever you want with this file.
.\"
.\" $FreeBSD: src/lib/libc/stdlib/lsearch.3,v 1.4 2002/12/19 09:40:24 ru Exp $
.\"
.Dd October 11, 2002
.Dt LSEARCH 3
.Os
.Sh NAME
.Nm lfind ,
.Nm lsearch
.Nd linear search and append
.Sh LIBRARY
.Lb libc
.Sh SYNOPSIS
.In search.h
.Ft "void *"
.Fo lfind
.Fa "const void *key" "const void *base" "size_t *nelp" "size_t width"
.Fa "int \*[lp]*compar\*[rp]\*[lp]const void *, const void *\*[rp]"
.Fc
.Ft "void *"
.Fo lsearch
.Fa "const void *key" "void *base" "size_t *nelp" "size_t width"
.Fa "int \*[lp]*compar\*[rp]\*[lp]const void *, const void *\*[rp]"
.Fc
.Sh DESCRIPTION
The
.Fn lsearch
and
.Fn lfind
functions walk linearly through an array, comparing each element with
the one to be sought, by means of a supplied comparison function.
.Pp
The
.Fa key
argument
points to an element that matches the one that is searched.
The array's address in memory is denoted by the
.Fa base
argument.
The width of one element (i.e., the size as returned by
.Fn sizeof )
is passed as the
.Fa width
argument.
The number of valid elements contained in the array (not the number of
elements the array has space reserved for) is given in the integer pointed
to by
.Fa nelp .
The
.Fa compar
argument points to a function which compares its two arguments and returns
zero if they are matching, and non-zero otherwise.
.Pp
If no matching element was found in the array,
.Fn lsearch
copies
.Fa key
into the position after the last element and increments the
integer pointed to by
.Fa nelp .
.Sh RETURN VALUES
The
.Fn lsearch
and
.Fn lfind
functions
return a pointer to the first element found.
If no element was found,
.Fn lsearch
returns a pointer to the newly added element, whereas
.Fn lfind
returns
.Dv NULL .
Both functions return
.Dv NULL
if an error occurs.
.Sh SEE ALSO
.Xr bsearch 3 ,
.Xr hsearch 3 ,
.Xr tsearch 3
.Sh HISTORY
The
.Fn lsearch
and
.Fn lfind
functions appeared in
.Bx 4.2 .
In
.Fx 5.0 ,
they reappeared conforming to
.St -p1003.1-2001 .
.Sh STANDARDS
The
.Fn lsearch
and
.Fn lfind
functions conform to
.St -p1003.1-2001 .
Commit	Line	Data
224c7076 A	1	.\"
	2	.\" Initial implementation:
	3	.\" Copyright (c) 2002 Robert Drehmel
	4	.\" All rights reserved.
	5	.\"
	6	.\" As long as the above copyright statement and this notice remain
	7	.\" unchanged, you can do what ever you want with this file.
	8	.\"
	9	.\" $FreeBSD: src/lib/libc/stdlib/lsearch.3,v 1.4 2002/12/19 09:40:24 ru Exp $
	10	.\"
	11	.Dd October 11, 2002
	12	.Dt LSEARCH 3
	13	.Os
	14	.Sh NAME
	15	.Nm lfind ,
	16	.Nm lsearch
	17	.Nd linear search and append
	18	.Sh LIBRARY
	19	.Lb libc
	20	.Sh SYNOPSIS
	21	.In search.h
	22	.Ft "void *"
	23	.Fo lfind
	24	.Fa "const void key" "const void base" "size_t *nelp" "size_t width"
	25	.Fa "int \[lp]compar\[rp]\[lp]const void , const void \*[rp]"
	26	.Fc
	27	.Ft "void *"
	28	.Fo lsearch
	29	.Fa "const void key" "void base" "size_t *nelp" "size_t width"
	30	.Fa "int \[lp]compar\[rp]\[lp]const void , const void \*[rp]"
	31	.Fc
	32	.Sh DESCRIPTION
	33	The
	34	.Fn lsearch
	35	and
	36	.Fn lfind
	37	functions walk linearly through an array, comparing each element with
	38	the one to be sought, by means of a supplied comparison function.
	39	.Pp
	40	The
	41	.Fa key
	42	argument
	43	points to an element that matches the one that is searched.
	44	The array's address in memory is denoted by the
	45	.Fa base
	46	argument.
	47	The width of one element (i.e., the size as returned by
	48	.Fn sizeof )
	49	is passed as the
	50	.Fa width
	51	argument.
	52	The number of valid elements contained in the array (not the number of
	53	elements the array has space reserved for) is given in the integer pointed
	54	to by
	55	.Fa nelp .
	56	The
	57	.Fa compar
	58	argument points to a function which compares its two arguments and returns
	59	zero if they are matching, and non-zero otherwise.
	60	.Pp
	61	If no matching element was found in the array,
	62	.Fn lsearch
	63	copies
	64	.Fa key
65	into the position after the last element and increments the
66	integer pointed to by
67	.Fa nelp .
68	.Sh RETURN VALUES
69	The
70	.Fn lsearch
71	and
72	.Fn lfind
73	functions
74	return a pointer to the first element found.
75	If no element was found,
76	.Fn lsearch
77	returns a pointer to the newly added element, whereas
78	.Fn lfind
79	returns
80	.Dv NULL .
81	Both functions return
82	.Dv NULL
83	if an error occurs.
84	.Sh SEE ALSO
85	.Xr bsearch 3 ,
86	.Xr hsearch 3 ,
87	.Xr tsearch 3
88	.Sh HISTORY
89	The
90	.Fn lsearch
91	and
92	.Fn lfind
93	functions appeared in
94	.Bx 4.2 .
95	In
96	.Fx 5.0 ,
97	they reappeared conforming to
98	.St -p1003.1-2001 .
99	.Sh STANDARDS
100	The
101	.Fn lsearch
102	and
103	.Fn lfind
104	functions conform to
105	.St -p1003.1-2001 .