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1.\" Copyright (c) 1990, 1991, 1993
2.\" The Regents of the University of California. 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.
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35.\"
36.\" @(#)strtoul.3 8.1 (Berkeley) 6/4/93
37.\" $FreeBSD: src/lib/libc/stdlib/strtoul.3,v 1.14 2001/09/11 09:39:23 ru Exp $
38.\"
39.Dd June 4, 1993
40.Dt STRTOUL 3
41.Os
42.Sh NAME
43.Nm strtoul , strtoull , strtouq
44.Nd "convert a string to an unsigned long, unsigned long long, or uquad_t integer"
45.Sh LIBRARY
46.Lb libc
47.Sh SYNOPSIS
48.In stdlib.h
49.In limits.h
50.Ft unsigned long
51.Fn strtoul "const char *nptr" "char **endptr" "int base"
52.Ft unsigned long long
53.Fn strtoull "const char *nptr" "char **endptr" "int base"
54.In sys/types.h
55.In stdlib.h
56.In limits.h
57.Ft u_quad_t
58.Fn strtouq "const char *nptr" "char **endptr" "int base"
59.Sh DESCRIPTION
60The
61.Fn strtoul
62function
63converts the string in
64.Fa nptr
65to an
66.Em unsigned long
67value.
68The
69.Fn strtoull
70function
71converts the string in
72.Fa nptr
73to an
74.Em unsigned long long
75value.
76The
77.Fn strtouq
78function
79converts the string in
80.Fa nptr
81to a
82.Em u_quad_t
83value.
84The conversion is done according to the given
85.Fa base ,
86which must be between 2 and 36 inclusive,
87or be the special value 0.
88.Pp
89The string may begin with an arbitrary amount of white space
90(as determined by
91.Xr isspace 3 )
92followed by a single optional
93.Ql +
94or
95.Ql -
96sign.
97If
98.Fa base
99is zero or 16,
100the string may then include a
101.Ql 0x
102prefix,
103and the number will be read in base 16; otherwise, a zero
104.Fa base
105is taken as 10 (decimal) unless the next character is
106.Ql 0 ,
107in which case it is taken as 8 (octal).
108.Pp
109The remainder of the string is converted to an
110.Em unsigned long
111value in the obvious manner,
112stopping at the end of the string
113or at the first character that does not produce a valid digit
114in the given base.
115(In bases above 10, the letter
116.Ql A
117in either upper or lower case
118represents 10,
119.Ql B
120represents 11, and so forth, with
121.Ql Z
122representing 35.)
123.Pp
124If
125.Fa endptr
126is non nil,
127.Fn strtoul
128stores the address of the first invalid character in
129.Fa *endptr .
130If there were no digits at all, however,
131.Fn strtoul
132stores the original value of
133.Fa nptr
134in
135.Fa *endptr .
136(Thus, if
137.Fa *nptr
138is not
139.Ql \e0
140but
141.Fa **endptr
142is
143.Ql \e0
144on return, the entire string was valid.)
145.Sh RETURN VALUES
146The
147.Fn strtoul
148or
149.Fn strtoull
150function
151returns either the result of the conversion
152or, if there was a leading minus sign,
153the negation of the result of the conversion,
154unless the original (non-negated) value would overflow;
155in the latter case,
156.Fn strtoul
157returns
158.Dv ULONG_MAX
159and
160.Fn strtoull
161returns
162.Dv ULLONG_MAX .
163In all cases,
164.Va errno
165is set to
166.Er ERANGE .
167If no conversion could be performed, 0 is returned and
168the global variable
169.Va errno
170is set to
171.Er EINVAL .
172.Sh ERRORS
173.Bl -tag -width Er
174.It Bq Er EINVAL
175The value of
176.Fa base
177is not supported or
178no conversion could be performed.
179.It Bq Er ERANGE
180The given string was out of range; the value converted has been clamped.
181.El
182.Sh SEE ALSO
183.Xr strtol 3
184.Sh STANDARDS
185The
186.Fn strtoul
187function
188conforms to
189.St -isoC .
190The
191.Fn strtoull
192function
193conforms to
194.St -isoC-99 .
195The
196.Bx
197.Fn strtoq
198function is deprecated.