xref: /netbsd-src/lib/libc/stdlib/strtoul.3 (revision 76dfffe33547c37f8bdd446e3e4ab0f3c16cea4b)
1.\"	$NetBSD: strtoul.3,v 1.6 1995/12/28 08:52:55 thorpej Exp $
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6.\" This code is derived from software contributed to Berkeley by
7.\" Chris Torek and the American National Standards Committee X3,
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38.\"     from: @(#)strtoul.3	5.4 (Berkeley) 6/25/92
39.\"
40.Dd June 25, 1992
41.Dt STRTOUL 3
42.Os
43.Sh NAME
44.Nm strtoul, strtouq
45.Nd convert a string to an unsigned long or uquad_t integer
46.Sh SYNOPSIS
47.Fd #include <stdlib.h>
48.Fd #include <limits.h>
49.Ft unsigned long
50.Fn strtoul "const char *nptr" "char **endptr" "int base"
51
52.Fd #include <sys/types.h>
53.Fd #include <stdlib.h>
54.Fd #include <limits.h>
55.Ft u_quad_t
56.Fn strtouq "const char *nptr" "char **endptr" "int base"
57.Sh DESCRIPTION
58The
59.Fn strtoul
60function
61converts the string in
62.Fa nptr
63to an
64.Em unsigned long
65value.
66The
67.Fn strtouq
68function
69converts the string in
70.Fa nptr
71to a
72.Em u_quad_t
73value.
74The conversion is done according to the given
75.Fa base ,
76which must be between 2 and 36 inclusive,
77or be the special value 0.
78.Pp
79The string may begin with an arbitrary amount of white space
80(as determined by
81.Xr isspace 3 )
82followed by a single optional
83.Ql +
84or
85.Ql -
86sign.
87If
88.Fa base
89is zero or 16,
90the string may then include a
91.Ql 0x
92prefix,
93and the number will be read in base 16; otherwise, a zero
94.Fa base
95is taken as 10 (decimal) unless the next character is
96.Ql 0 ,
97in which case it is taken as 8 (octal).
98.Pp
99The remainder of the string is converted to an
100.Em unsigned long
101value in the obvious manner,
102stopping at the end of the string
103or at the first character that does not produce a valid digit
104in the given base.
105(In bases above 10, the letter
106.Ql A
107in either upper or lower case
108represents 10,
109.Ql B
110represents 11, and so forth, with
111.Ql Z
112representing 35.)
113.Pp
114If
115.Fa endptr
116is non nil,
117.Fn strtoul
118stores the address of the first invalid character in
119.Fa *endptr .
120If there were no digits at all, however,
121.Fn strtoul
122stores the original value of
123.Fa nptr
124in
125.Fa *endptr .
126(Thus, if
127.Fa *nptr
128is not
129.Ql \e0
130but
131.Fa **endptr
132is
133.Ql \e0
134on return, the entire string was valid.)
135.Sh RETURN VALUES
136The
137.Fn strtoul
138function
139returns either the result of the conversion
140or, if there was a leading minus sign,
141the negation of the result of the conversion,
142unless the original (non-negated) value would overflow;
143in the latter case,
144.Fn strtoul
145returns
146.Dv ULONG_MAX
147and sets the global variable
148.Va errno
149to
150.Er ERANGE .
151.Sh ERRORS
152.Bl -tag -width Er
153.It Bq Er ERANGE
154The given string was out of range; the value converted has been clamped.
155.El
156.Sh SEE ALSO
157.Xr strtol 3
158.Sh STANDARDS
159The
160.Fn strtoul
161function
162conforms to
163.St -ansiC .
164.Sh BUGS
165Ignores the current locale.
166