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wcstol(3)
NAME
wcstol - Convert a wide-character string to long integer
SYNOPSIS
#include <wchar.h>
long int wcstol(
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:
wcstol(): XSH5.0
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 a
long integer representation.
endptr
Points to a pointer in which the wcstol() 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 characters are interpreted.
DESCRIPTION
The wcstol() function converts the initial portion of the wide-character
string pointed to by the nptr parameter to a 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 integer and the result is
returned.
The base parameter can take values between 0 and 36.
· 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
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. 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 space characters
(as determined by theiswspace() function). Any nonspace character is the
start of a potential subject string that may form an 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 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 was the POSIX (C) locale. (Current industry
standards allow conforming implementations to support forms of subject
sequences in addition to those in the POSIX (C) locale. On Tru64 UNIX
systems, this additional support is unnecessary.)
RETURN VALUES
If the wcstol() function finds the expected subject form, the converted
value of long integer is returned. The function returns 0 (zero) if it does
not convert the subject value. If the converted value is outside the range
of representable values, the function returns LONG_MAX or LONG_MIN
(according to the sign of the subject value).
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, wcstol() stores the
nptr pointer in the *endptr parameter.
Since 0 (zero), LONG_MIN, and LONG_MAX are returned in the event of an
error and are also valid returns if the wcstol() function is successful,
applications should set errno to 0 (zero) before each call to the wcstol()
function, and check errno after each return from the wcstol() 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 wcstol() function sets errno
to the corresponding value:
[EINVAL]
The base parameter has an unsupported value (less than 0 or greater
than 36).
[Tru64 UNIX] 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 a signed long
integer:
#include <stdio.h>
#include <wchar.h>
#include <locale.h>
#include <errno.h>
#define WLENGTH 40
main
{
wchar_t WCString[WLENGTH], *endptr;
long int retval;
(void)setlocale(LC_ALL, "");
if (fgetws(WCString, WLENGTH, stdin) != NULL) {
errno = 0;
retval = wcstol ( WCString, &endptr, 0 );
if (retval == 0 && (errno != 0
|| WCString == endptr)) {
/* No conversion could be performed */
printf("No conversion performed\n");
} else if (errno != 0 && (retval == LONG_MAX
|| retval == LONG_MIN)) {
/* Error handling */
} else {
/* retval contains long integer */
printf("Integer in decimal is %d\n", retval);
}
}
}
SEE ALSO
Functions: atoi(3), iswalnum(3), scanf(3), wcstod(3), wcstoul(3),
wctype(3), wscanf(3)
Standards: standards(5)
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