man pages section 3: Basic Library Functions

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Updated: July 2014
 
 

wcstol(3C)

Name

wcstol, wcstoll, wstol, watol, watoll, watoi - convert wide character string to long integer

Synopsis

#include <wchar.h> 

long wcstol(const wchar_t *restrict nptr, wchar_t **restrict endptr,
     int base);
long long wcstoll(const wchar_t *restrict nptr, wchar_t **restrict endptr,
     int base);
#include <widec.h> 

long wstol(const wchar_t *nptr, wchar_t **endptr, int base);
long watol(wchar_t *nptr);
long long watoll(wchar_t *nptr);
int watoi(wchar_t *nptr);

Description

The wcstol() and wcstoll() functions convert the initial portion of the wide character string pointed to by nptr to long and long long representation, respectively. They first decompose the input string into three parts:

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

  2. a subject 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 unrecognised 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 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, octal constant or hexadecimal constant, any of which may be preceded by a `+' or `−' 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 `−' 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 code representations of `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 non-white-space wide-character code, that 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 code, or if the first non-white-space wide-character code 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.

These functions do not change the setting of errno if successful.

Since 0, {LONG_MIN} or {LLONG_MIN}, and {LONG_MAX} or {LLONG_MAX} are returned on error and are also valid returns on success, an application wanting to check for error situations should set errno to 0, call one of these functions, then check errno.

The wstol() function is equivalent to wcstol().

The watol() function is equivalent to wstol(str,(wchar_t **)NULL, 10).

The watoll() function is the long-long (double long) version of watol().

The watoi() function is equivalent to (int)watol( ).

Return Values

Upon successful completion, these functions 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, {LONG_MIN}, {LONG_MAX}, {LLONG_MIN}, or {LLONG_MAX} is returned (according to the sign of the value), and errno is set to ERANGE.

Errors

These functions will fail if:

EINVAL

The value of base is not supported.

ERANGE

The value to be returned is not representable.

These functions may fail if:

EINVAL

No conversion could be performed.

Attributes

See attributes(5) for descriptions of the following attributes:

ATTRIBUTE TYPE
ATTRIBUTE VALUE
Interface Stability
wcstol() and wcstoll() are Standard.
MT-Level
MT-Safe

See Also

iswalpha(3C), iswspace(3C), scanf(3C), wcstod(3C), attributes(5), standards(5)

Notes

Truncation from long long to long can take place upon assignment or by an explicit cast.