Tribblix: manual page: wcstoul.3c

WCSTOUL(3C) Standard C Library Functions WCSTOUL(3C)

NAME

wcstoul, wcstoull - convert wide-character string to unsigned long

SYNOPSIS

#include <wchar.h>

unsigned long wcstoul(const wchar_t *restrict nptr,
wchar_t **restrict endptr, int base);

unsigned long long wcstoull(const wchar_t *restrict nptr,
wchar_t **restrict endptr, int base);

DESCRIPTION

The wcstoul() and wcstoull() functions convert the initial portion of
the wide-character string pointed to by nptr to unsigned long and
unsigned long long representation, respectively. First they decompose
the input wide-character string into three parts:

1. An initial, possibly empty, sequence of white-space wide-
character codes (as specified by the function
iswspace(3C))

2.
Asubject sequence interpreted as an integer represented
in some radix determined by the value of base

3. a final wide-character string of one or more unrecognized
wide-character codes, including the terminating null wide-
character code of the input wide character string

They then attempt to convert the subject sequence to an unsigned
integer and return the result.

If the value of base is 0, the expected form of the subject sequence
is that of a decimal constant, an octal constant, or a hexadecimal
constant, any of which may be preceded by a `+' or a `-' sign. A
decimal constant begins with a non-zero digit, and consists of a
sequence of decimal digits. An octal constant consists of the prefix
`0', optionally followed by a sequence of the digits `0' to `7' only.
A hexadecimal constant consists of the prefix `0x' or `0X', followed
by a sequence of the decimal digits and letters `a' (or `A') to `f'
(or `F'), with values 10 to 15, respectively.

If the value of base is between 2 and 36, the expected form of the
subject sequence is a sequence of letters and digits representing an
integer with the radix specified by base, optionally preceded by a
`+' or a `-' sign, but not including an integer suffix. The letters
from `a' (or `A') to `z' (or `Z') inclusive are ascribed the values
10 to 35; only letters whose ascribed values are less than that of
base are permitted. If the value of base is 16, the wide-character
codes `0x' or `0X' may optionally precede the sequence of letters and
digits, following the sign, if present.

The subject sequence is defined as the longest initial subsequence of
the input wide-character string, starting with the first wide-
character code that is not a white space and is of the expected form.
The subject sequence contains no wide-character codes if the input
wide-character string is empty or consists entirely of white-space
wide-character codes, or if the first wide-character code that is not
a white space is other than a sign or a permissible letter or digit.

If the subject sequence has the expected form and the value of base
is 0, the sequence of wide-character codes starting with the first
digit is interpreted as an integer constant. If the subject sequence
has the expected form and the value of base is between 2 and 36, it
is used as the base for conversion, ascribing to each letter its
value as given above. If the subject sequence begins with a minus
sign, the value resulting from the conversion is negated. A pointer
to the final wide character string is stored in the object pointed
to by endptr, provided that endptr is not a null pointer.

If the subject sequence is empty or does not have the expected form,
no conversion is performed; the value of nptr is stored in the object
pointed to by endptr, provided that endptr is not a null pointer.

The wcstoul() function does not change the setting of errno if
successful.

Since 0, {ULONG_MAX}, and {ULLONG_MAX} are returned on error and 0 is
also a valid return on success, an application wanting to check for
error situations should set errno to 0, then call wcstoul() or
wcstoull(), then check errno.

The wcstoul() and wcstoull() functions do not change the setting of
errno if successful.

RETURN VALUE

Upon successful completion, wcstoul() and wcstoull() return the
converted value, if any. If no conversion could be performed, 0 is
returned and errno may be set to indicate the error. If the correct
value is outside the range of representable values, {ULONG_MAX} or
{ULLONG_MAX}, respectively, is returned and errno is set to ERANGE.

ERRORS

The wcstoul() and wcstoull() functions will fail if:

EINVAL
The value of base is not supported.

ERANGE
The value to be returned is not representable.

The wcstoul() and wcstoull() functions may fail if:

EINVAL
No conversion could be performed.

USAGE

Unlike wcstod(3C) and wcstol(3C), wcstoul() and wcstoull() must
always return a non-negative number; using the return value of
wcstoul() for out-of-range numbers with wcstoul() or wcstoull() could
cause more severe problems than just loss of precision if those
numbers can ever be negative.

ATTRIBUTES