[apple/libc.git] / stdlib / FreeBSD / strtonum.3

.\" Copyright (c) 2004 Ted Unangst
.\"
.\" Permission to use, copy, modify, and distribute this software for any
.\" purpose with or without fee is hereby granted, provided that the above
.\" copyright notice and this permission notice appear in all copies.
.\"
.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
.\"
.\" $OpenBSD: strtonum.3,v 1.13 2006/04/25 05:15:42 tedu Exp $
.\" $FreeBSD$
.\"
.Dd April 29, 2004
.Dt STRTONUM 3
.Os
.Sh NAME
.Nm strtonum
.Nd "reliably convert string value to an integer"
.Sh SYNOPSIS
.In stdlib.h
.Ft long long
.Fo strtonum
.Fa "const char *nptr"
.Fa "long long minval"
.Fa "long long maxval"
.Fa "const char **errstr"
.Fc
.Sh DESCRIPTION
The
.Fn strtonum
function converts the string in
.Fa nptr
to a
.Vt "long long"
value.
The
.Fn strtonum
function was designed to facilitate safe, robust programming
and overcome the shortcomings of the
.Xr atoi 3
and
.Xr strtol 3
family of interfaces.
.Pp
The string may begin with an arbitrary amount of whitespace
(as determined by
.Xr isspace 3 )
followed by a single optional
.Ql +
or
.Ql -
sign.
.Pp
The remainder of the string is converted to a
.Vt "long long"
value according to base 10.
.Pp
The value obtained is then checked against the provided
.Fa minval
and
.Fa maxval
bounds.
If
.Fa errstr
is non-null,
.Fn strtonum
stores an error string in
.Fa *errstr
indicating the failure.
.Sh RETURN VALUES
The
.Fn strtonum
function returns the result of the conversion,
unless the value would exceed the provided bounds or is invalid.
On error, 0 is returned,
.Va errno
is set, and
.Fa errstr
will point to an error message.
On success,
.Fa *errstr
will be set to
.Dv NULL ;
this fact can be used to differentiate
a successful return of 0 from an error.
.Sh EXAMPLES
Using
.Fn strtonum
correctly is meant to be simpler than the alternative functions.
.Bd -literal -offset indent
int iterations;
const char *errstr;

iterations = strtonum(optarg, 1, 64, &errstr);
if (errstr != NULL)
	errx(1, "number of iterations is %s: %s", errstr, optarg);
.Ed
.Pp
The above example will guarantee that the value of iterations is between
1 and 64 (inclusive).
.Sh ERRORS
.Bl -tag -width Er
.It Bq Er ERANGE
The given string was out of range.
.It Bq Er EINVAL
The given string did not consist solely of digit characters.
.It Bq Er EINVAL
The supplied
.Fa minval
was larger than
.Fa maxval .
.El
.Pp
If an error occurs,
.Fa errstr
will be set to one of the following strings:
.Pp
.Bl -tag -width ".Li too large" -compact
.It Li "too large"
The result was larger than the provided maximum value.
.It Li "too small"
The result was smaller than the provided minimum value.
.It Li invalid
The string did not consist solely of digit characters.
.El
.Sh SEE ALSO
.Xr atof 3 ,
.Xr atoi 3 ,
.Xr atol 3 ,
.Xr atoll 3 ,
.Xr sscanf 3 ,
.Xr strtod 3 ,
.Xr strtol 3 ,
.Xr strtoul 3
.Sh STANDARDS
The
.Fn strtonum
function is a
.Bx
extension.
The existing alternatives, such as
.Xr atoi 3
and
.Xr strtol 3 ,
are either impossible or difficult to use safely.
.Sh HISTORY
The
.Fn strtonum
function first appeared in
.Ox 3.6 .
Commit	Line	Data
a9aaacca A	1	.\" Copyright (c) 2004 Ted Unangst
	2	.\"
	3	.\" Permission to use, copy, modify, and distribute this software for any
	4	.\" purpose with or without fee is hereby granted, provided that the above
	5	.\" copyright notice and this permission notice appear in all copies.
	6	.\"
	7	.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
	8	.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
	9	.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
	10	.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
	11	.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
	12	.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
	13	.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
	14	.\"
	15	.\" $OpenBSD: strtonum.3,v 1.13 2006/04/25 05:15:42 tedu Exp $
	16	.\" $FreeBSD$
	17	.\"
	18	.Dd April 29, 2004
	19	.Dt STRTONUM 3
	20	.Os
	21	.Sh NAME
	22	.Nm strtonum
	23	.Nd "reliably convert string value to an integer"
	24	.Sh SYNOPSIS
	25	.In stdlib.h
	26	.Ft long long
	27	.Fo strtonum
	28	.Fa "const char *nptr"
	29	.Fa "long long minval"
	30	.Fa "long long maxval"
	31	.Fa "const char **errstr"
	32	.Fc
	33	.Sh DESCRIPTION
	34	The
	35	.Fn strtonum
	36	function converts the string in
	37	.Fa nptr
	38	to a
	39	.Vt "long long"
	40	value.
	41	The
	42	.Fn strtonum
	43	function was designed to facilitate safe, robust programming
	44	and overcome the shortcomings of the
	45	.Xr atoi 3
	46	and
	47	.Xr strtol 3
	48	family of interfaces.
	49	.Pp
	50	The string may begin with an arbitrary amount of whitespace
	51	(as determined by
	52	.Xr isspace 3 )
	53	followed by a single optional
	54	.Ql +
	55	or
	56	.Ql -
	57	sign.
	58	.Pp
	59	The remainder of the string is converted to a
	60	.Vt "long long"
	61	value according to base 10.
	62	.Pp
	63	The value obtained is then checked against the provided
	64	.Fa minval
65	and
66	.Fa maxval
67	bounds.
68	If
69	.Fa errstr
70	is non-null,
71	.Fn strtonum
72	stores an error string in
73	.Fa *errstr
74	indicating the failure.
75	.Sh RETURN VALUES
76	The
77	.Fn strtonum
78	function returns the result of the conversion,
79	unless the value would exceed the provided bounds or is invalid.
80	On error, 0 is returned,
81	.Va errno
82	is set, and
83	.Fa errstr
84	will point to an error message.
85	On success,
86	.Fa *errstr
87	will be set to
88	.Dv NULL ;
89	this fact can be used to differentiate
90	a successful return of 0 from an error.
91	.Sh EXAMPLES
92	Using
93	.Fn strtonum
94	correctly is meant to be simpler than the alternative functions.
95	.Bd -literal -offset indent
96	int iterations;
97	const char *errstr;
98
99	iterations = strtonum(optarg, 1, 64, &errstr);
100	if (errstr != NULL)
101	errx(1, "number of iterations is %s: %s", errstr, optarg);
102	.Ed
103	.Pp
104	The above example will guarantee that the value of iterations is between
105	1 and 64 (inclusive).
106	.Sh ERRORS
107	.Bl -tag -width Er
108	.It Bq Er ERANGE
109	The given string was out of range.
110	.It Bq Er EINVAL
111	The given string did not consist solely of digit characters.
112	.It Bq Er EINVAL
113	The supplied
114	.Fa minval
115	was larger than
116	.Fa maxval .
117	.El
118	.Pp
119	If an error occurs,
120	.Fa errstr
121	will be set to one of the following strings:
122	.Pp
123	.Bl -tag -width ".Li too large" -compact
124	.It Li "too large"
125	The result was larger than the provided maximum value.
126	.It Li "too small"
127	The result was smaller than the provided minimum value.
128	.It Li invalid
129	The string did not consist solely of digit characters.
130	.El
131	.Sh SEE ALSO
132	.Xr atof 3 ,
133	.Xr atoi 3 ,
134	.Xr atol 3 ,
135	.Xr atoll 3 ,
136	.Xr sscanf 3 ,
137	.Xr strtod 3 ,
138	.Xr strtol 3 ,
139	.Xr strtoul 3
140	.Sh STANDARDS
141	The
142	.Fn strtonum
143	function is a
144	.Bx
145	extension.
146	The existing alternatives, such as
147	.Xr atoi 3
148	and
149	.Xr strtol 3 ,
150	are either impossible or difficult to use safely.
151	.Sh HISTORY
152	The
153	.Fn strtonum
154	function first appeared in
155	.Ox 3.6 .