xref: /netbsd-src/lib/libc/stdlib/strtoul.3 (revision 4472dbe5e3bd91ef2540bada7a7ca7384627ff9b)
1.\"	$NetBSD: strtoul.3,v 1.11 2000/03/06 18:32:33 kleink Exp $
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38.\"     from: @(#)strtoul.3	8.1 (Berkeley) 6/4/93
39.\"
40.Dd March 6, 2000
41.Dt STRTOUL 3
42.Os
43.Sh NAME
44.Nm strtoul ,
45.Nm strtoull ,
46.Nm strtouq
47.Nd "convert a string to an unsigned long, unsigned long long or uquad_t integer"
48.Sh LIBRARY
49.Lb libc
50.Sh SYNOPSIS
51.Fd #include <stdlib.h>
52.Fd #include <limits.h>
53.Ft unsigned long int
54.Fn strtoul "const char *nptr" "char **endptr" "int base"
55.Ft unsigned long long int
56.Fn strtoull "const char *nptr" "char **endptr" "int base"
57
58.Fd #include <sys/types.h>
59.Fd #include <stdlib.h>
60.Fd #include <limits.h>
61.Ft u_quad_t
62.Fn strtouq "const char *nptr" "char **endptr" "int base"
63.Sh DESCRIPTION
64The
65.Fn strtoul
66function
67converts the string in
68.Fa nptr
69to an
70.Em unsigned long int
71value.
72The
73.Fn strtoull
74function
75converts the string in
76.Fa nptr
77to an
78.Em unsigned long long int
79value.
80The
81.Fn strtouq
82function
83converts the string in
84.Fa nptr
85to a
86.Em u_quad_t
87value.
88The conversion is done according to the given
89.Fa base ,
90which must be between 2 and 36 inclusive,
91or be the special value 0.
92.Pp
93The string may begin with an arbitrary amount of white space
94(as determined by
95.Xr isspace 3 )
96followed by a single optional
97.Ql +
98or
99.Ql -
100sign.
101If
102.Fa base
103is zero or 16,
104the string may then include a
105.Ql 0x
106prefix,
107and the number will be read in base 16; otherwise, a zero
108.Fa base
109is taken as 10 (decimal) unless the next character is
110.Ql 0 ,
111in which case it is taken as 8 (octal).
112.Pp
113The remainder of the string is converted to an
114.Em unsigned long
115value in the obvious manner,
116stopping at the end of the string
117or at the first character that does not produce a valid digit
118in the given base.
119(In bases above 10, the letter
120.Ql A
121in either upper or lower case
122represents 10,
123.Ql B
124represents 11, and so forth, with
125.Ql Z
126representing 35.)
127.Pp
128If
129.Fa endptr
130is non nil,
131.Fn strtoul
132stores the address of the first invalid character in
133.Fa *endptr .
134If there were no digits at all, however,
135.Fn strtoul
136stores the original value of
137.Fa nptr
138in
139.Fa *endptr .
140(Thus, if
141.Fa *nptr
142is not
143.Ql \e0
144but
145.Fa **endptr
146is
147.Ql \e0
148on return, the entire string was valid.)
149.Sh RETURN VALUES
150The
151.Fn strtoul
152function
153returns either the result of the conversion
154or, if there was a leading minus sign,
155the negation of the result of the conversion,
156unless the original (non-negated) value would overflow;
157in the latter case,
158.Fn strtoul
159returns
160.Dv ULONG_MAX
161and sets the global variable
162.Va errno
163to
164.Er ERANGE .
165.Sh ERRORS
166.Bl -tag -width Er
167.It Bq Er ERANGE
168The given string was out of range; the value converted has been clamped.
169.El
170.Sh SEE ALSO
171.Xr strtol 3
172.Xr strtoll 3
173.Sh STANDARDS
174The
175.Fn strtoul
176function
177conforms to
178.St -ansiC .
179The
180.Fn strtoull
181function
182conforms to
183.St -isoC99 .
184.Sh BUGS
185Ignores the current locale.
186