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1.\" Copyright (c) 1990, 1991 The Regents of the University of California.
2.\" All rights reserved.
3.\"
4.\" This code is derived from software contributed to Berkeley by
5.\" Chris Torek and the American National Standards Committee X3,
6.\" on Information 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.\" $OpenBSD: strtol.3,v 1.13 2003/06/02 20:18:38 millert Exp $
33.\"
34.Dd June 25, 1992
35.Dt STRTOL 3
36.Os
37.Sh NAME
38.Nm strtol ,
39.Nm strtoll ,
40.Nm strtoq
41.Nd "convert string value to a long or long long integer"
42.Sh SYNOPSIS
43.Fd #include <stdlib.h>
44.Fd #include <limits.h>
45.Ft long
46.Fn strtol "const char *nptr" "char **endptr" "int base"
47.Pp
48.Fd #include <stdlib.h>
49.Fd #include <limits.h>
50.Ft long long
51.Fn strtoll "const char *nptr" "char **endptr" "int base"
52.Pp
53.Fd #include <sys/types.h>
54.Fd #include <stdlib.h>
55.Fd #include <limits.h>
56.Ft quad_t
57.Fn strtoq "const char *nptr" "char **endptr" "int base"
58.Sh DESCRIPTION
59The
60.Fn strtol
61function converts the string in
62.Fa nptr
63to a
64.Li long
65value.
66The
67.Fn strtoll
68function converts the string in
69.Fa nptr
70to a
71.Li long long
72value.
73The
74.Fn strtoq
75function is a deprecated equivalent of
76.Fn strtoll
77and is provided for backwards compatibility with legacy programs.
78The conversion is done according to the given
79.Fa base ,
80which must be a number between 2 and 36 inclusive or the special value 0.
81.Pp
82The string may begin with an arbitrary amount of whitespace
83(as determined by
84.Xr isspace 3 )
85followed by a single optional
86.Ql +
87or
88.Ql -
89sign.
90If
91.Fa base
92is zero or 16, the string may then include a
93.Ql 0x
94prefix, and the number will be read in base 16; otherwise, a zero
95.Fa base
96is taken as 10 (decimal) unless the next character is
97.Ql 0 ,
98in which case it is taken as 8 (octal).
99.Pp
100The remainder of the string is converted to a
101.Li long
102value in the obvious manner,
103stopping at the first character which is not a valid digit
104in the given base.
105(In bases above 10, the letter
106.Ql A
107in either upper or lower case represents 10,
108.Ql B
109represents 11, and so forth, with
110.Ql Z
111representing 35.)
112.Pp
113If
114.Fa endptr
115is non-null,
116.Fn strtol
117stores the address of the first invalid character in
118.Fa *endptr .
119If there were no digits at all, however,
120.Fn strtol
121stores the original value of
122.Fa nptr
123in
124.Fa *endptr .
125(Thus, if
126.Fa *nptr
127is not
128.Ql \e0
129but
130.Fa **endptr
131is
132.Ql \e0
133on return, the entire string was valid.)
134.Sh RETURN VALUES
135The
136.Fn strtol
137function returns the result of the conversion,
138unless the value would underflow or overflow.
139If an underflow occurs,
140.Fn strtol
141returns
142.Dv LONG_MIN .
143If an overflow occurs,
144.Fn strtol
145returns
146.Dv LONG_MAX .
147In both cases,
148.Va errno
149is set to
150.Er ERANGE .
151.Pp
152The
153.Fn strtoll
154function has identical return values except that
155.Dv LLONG_MIN
156and
157.Dv LLONG_MAX
158are used to indicate underflow and overflow respectively.
159.Sh EXAMPLES
160Ensuring that a string is a valid number (i.e., in range and containing no
161trailing characters) requires clearing
162.Va errno
163beforehand explicitly since
164.Va errno
165is not changed on a successful call to
166.Fn strtol ,
167and the return value of
168.Fn strtol
169cannot be used unambiguously to signal an error:
170.Bd -literal -offset indent
171char *ep;
172long lval;
173
174\&...
175
176errno = 0;
177lval = strtol(buf, &ep, 10);
178if (buf[0] == '\e0' || *ep != '\e0')
179 goto not_a_number;
180if (errno == ERANGE && (lval == LONG_MAX || lval == LONG_MIN))
181 goto out_of_range;
182.Ed
183.Pp
184This example will accept
185.Dq 12
186but not
187.Dq 12foo
188or
189.Dq 12\en .
190If trailing whitespace is acceptable, further checks must be done on
191.Va *ep ;
192alternately, use
193.Xr sscanf 3 .
194.Pp
195If
196.Fn strtol
197is being used instead of
198.Xr atoi 3 ,
199error checking is further complicated because the desired return value is an
200.Li int
201rather than a
202.Li long ;
203however, on some architectures integers and long integers are the same size.
204Thus the following is necessary:
205.Bd -literal -offset indent
206char *ep;
207int ival;
208long lval;
209
210\&...
211
212errno = 0;
213lval = strtol(buf, &ep, 10);
214if (buf[0] == '\e0' || *ep != '\e0')
215 goto not_a_number;
216if ((errno == ERANGE && (lval == LONG_MAX || lval == LONG_MIN)) ||
217 (lval > INT_MAX || lval < INT_MIN))
218 goto out_of_range;
219ival = lval;
220.Ed
221.Sh ERRORS
222.Bl -tag -width Er
223.It Bq Er ERANGE
224The given string was out of range; the value converted has been clamped.
225.El
226.Sh SEE ALSO
227.Xr atof 3 ,
228.Xr atoi 3 ,
229.Xr atol 3 ,
230.Xr atoll 3 ,
231.Xr sscanf 3 ,
232.Xr strtod 3 ,
233.Xr strtoul 3
234.Sh STANDARDS
235The
236.Fn strtol
237and
238.Fn strtoll
239functions conform to
240.St -ansiC-99 .
241The
242.Fn strtoq
243function is a
244.Bx
245extension and is provided for backwards compatibility with legacy programs.
246.Sh BUGS
247Ignores the current locale.