usr/src/lib/libc/stdlib/strtoul.3

.\" Copyright (c) 1990 The Regents of the University of California.
.\" All rights reserved.
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.\" This code is derived from software contributed to Berkeley by
.\" Chris Torek.
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.\"     @(#)strtoul.3   5.1 (Berkeley) 5/15/90
.\"
.TH STRTOUL 3 "May 15, 1990"
.UC 7
.SH NAME
strtoul \- convert a string to an unsigned long integer
.SH SYNOPSIS
.B #include <stdlib.h>
.br
.B #include <limits.h>
.PP
.B "unsigned long strtoul(char *nptr, char **endptr, int base);
.SH DESCRIPTION
.B Strtoul
converts the string in
.I nptr
to an
.B "unsigned long"
value according to the given
.IR base ,
which must be between 2 and 36 inclusive,
or be the special value 0.
.PP
The string may begin with an arbitrary amount of white space
(as determined by
.BR isspace ;
see
.IR ctype (3)),
followed by a single optional `+' or `-' sign.
If
.I base
is zero or 16,
the string may then include a `0x' prefix,
and the number will be read in base 16; otherwise, a zero
.I base
is taken as 10 (decimal) unless the next character is `0',
in which case it is taken as 8 (octal).
.PP
The remainder of the string is converted to an
.B "unsigned long"
value in the obvious manner,
stopping at the end of the string
or at the first character that does not produce a valid digit
in the given base.
(In bases above 10, the letter `A' in either upper or lower case
represents 10, `B' represents 11, and so forth, with `Z' representing 35.)
.PP
If
.I endptr
is non nil,
.B strtoul
stores the address of the first invalid character in
.IR *endptr .
If there were no digits at all, however,
.B strtoul
stores the original value of
.I nptr
in
.IR *endptr .
(Thus, if
.I *nptr
is not '\e0' but
.IR **endptr
is '\e0' on return, the entire string was valid.)
.SH RETURN VALUE
.B Strtoul
returns either the result of the conversion
or, if there was a leading minus sign,
the negation of the result of the conversion,
unless the original (non-negated) value would overflow;
in the latter case,
.B strtoul
returns
.B ULONG_MAX
and sets
.B errno
to
.BR ERANGE .
.SH ERRORS
.TP
[ERANGE]
The given string was out of range; the value converted has been clamped.
.SH SEE ALSO
strtol(3)
.SH STANDARDS
.B Strtoul
conforms to ANSI X3.159-1989 (``ANSI C'').
.SH BUGS
Ignores the current locale.