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wcstoul(3)
NAME
wcstoul - Convert wide-character strings to unsigned long integer
SYNOPSIS
#include <wchar.h>
unsigned long int wcstoul(
const wchar_t *nptr,
wchar_t **endptr,
int base );
LIBRARY
Standard C Library (libc)
STANDARDS
Interfaces documented on this reference page conform to industry standards
as follows:
wcstoul(): ISO C, XPG4
Refer to the standards(5) reference page for more information about
industry standards and associated tags.
PARAMETERS
nptr
Contains a pointer to the wide-character string to be converted to an
unsigned long integer.
endptr
Points to a pointer in which the wcstoul() function stores the position
in the string specified by the nptr parameter where a wide character is
found that is not a valid character for the purpose of this conversion.
base
Specifies the radix in which the wide characters are interpreted.
DESCRIPTION
The wcstoul() function converts the initial portion of the wide-character
string pointed to by the nptr parameter to an unsigned long integer
representation. The input wide-character string is first broken down into
three parts:
· White space--An initial (possibly empty) sequence of wide-character
spaces (as specified by the iswspace() function)
· Subject sequence--A sequence of wide characters that are valid in an
integer constant of the radix determined by the base parameter
· Unrecognized characters--A final sequence of unrecognized wide-
character codes, including the terminating null wide character
If possible, the subject is then converted to an unsigned integer and the
result is returned.
The base parameter can take values between 0 and 36 to indicate the
following:
· If the base value is 0 (zero), the subject string can be a decimal,
octal, or hexadecimal integer constant. A decimal constant begins with
a nonzero digit and consists of a sequence of decimal digits. An octal
constant consists of the prefix 0 (zero) optionally followed by a
sequence of digits in the range 0 through 7. A hexadecimal constant
consists of the prefix 0x or oX followed by a sequence consisting of
decimal digits and the letters in the range a (or A) to f (or F).
· If the base value is between 2 and 36, the subject string can be a
sequence of digits and the letters a (or A) to z ( or Z ) that are
used to represent an integer in the specified base. Alphabetic
characters represent digits with an equivalent decimal value from 10
(for the letter A) to 35 (for the letter Z). The subject string can
have only digits with a value less than base and alphabetic characters
with equivalent values less than base. For example, when the value of
the base parameter is 20, only the following value assignments are
converted.
Character 0 1 2 3 4 5 6 7 8 9 A B C D E F G H I J
a b c d e f g h i j
base Value 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19
The subject string can optionally be preceded by a + (plus sign) or -
(minus sign), but cannot include an integer suffix (such as L). If the
subject string is preceded by a - (minus sign), the converted integer value
has a negative value cast to unsigned integer. If the value of base is 16,
the characters 0x or 0X may optionally precede the sequence of letters or
digits, following the sign, if present.
The wide-character string is parsed to skip the initial white-space
characters (as determined by the iswspace() function). Any nonspace
character is the start of a potential subject string that may form an
unsigned long integer in the base specified by the base parameter. The
subject sequence is defined to be the longest initial substring that is of
the expected form of unsigned long integer. Any character that does not
satisfy this expected form begins the final sequence of unrecognized
characters. The wcstol() function sets the *endptr parameter to point to
this final sequence of unrecognized characters.
If the subject sequence is empty or does not have the expected form, the
function performs no conversion. In this case, provided that endptr is not
a null pointer, the function stores the value of nptr in the object pointed
to by endptr.
The LC_CTYPE category of the locale controls which wide characters are
treated as spaces but does not affect the interpretation of characters as
part of the subject string. The characters in the subject string are always
treated as if the locale were the C locale. (Current industry standards
allow, but do not require, conforming implementations to support forms of
subject sequences outside the base range that is supported by the POSIX
locale. Keep this fact in mind when developing applications to run on
different vendors' systems.)
RETURN VALUES
The wcstoul() function returns the converted value of the unsigned integer
if the expected form is found. If no conversion could be performed, a value
of 0 (zero) is returned. If the converted value is outside the range of
representable values, ULONG_MAX is returned.
If the endptr parameter is not a null pointer, wcstol() stores a pointer to
the final sequence of unrecognized characters in *endptr except when the
subject sequence is empty or invalid. In this case, wcstoul() stores the
nptr pointer in the *endptr parameter.
Since 0 (zero) and ULONG_MAX are returned in the event of an error and are
also valid returns if the wcstoul() function is successful, applications
should set errno to 0 (zero) before calling the wcstoul() function and
check errno after each return from the wcstoul() function. If errno is
nonzero, an error occurred. Additionally, if 0 (zero) is returned,
applications should check if the endptr parameter equals the nptr
parameter. In this case, there was no valid subject string.
ERRORS
If any of the following conditions occur, the wcstoul() function sets errno
to the corresponding value:
[EINVAL]
The base parameter has a value less than 0 or greater than 36.
The nptr parameter is a null pointer.
[ERANGE]
The converted value is outside the range of representable values.
EXAMPLES
The following example converts a wide-character string to unsigned long
integer:
#include <stdio.h>
#include <wchar.h>
#include <locale.h>
#include <errno.h>
#define WLENGTH 40
main()
{
wchar_t WCString[WLENGTH], *endptr;
unsigned long int retval;
(void)setlocale(LC_ALL, " ");
if (fgetws(WCString, WLENGTH, stdin) != NULL) {
errno = 0;
retval = wcstoul ( WCString, &endptr, 0 );
if (retval == 0 && (errno != 0
|| WCString == endptr)) {
/* No conversion could be performed */
printf("No conversion performed\n");
} else if (retval == ULONG_MAX && errno != 0 ) {
/* Error handling */
} else {
/* retval contains an unsigned long integer */
printf("Unsigned integer in decimal is %lx\n", retval);
}
}
}
SEE ALSO
Functions: atoi(3), iswalnum(3), scanf(3), wcstod(3), wcstol(3), wctype(3),
wscanf(3)
Standards: standards(5)
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