код символа (перезапускаемый) (character code (restartable))
Пролог (Prolog)
This manual page is part of the POSIX Programmer's Manual. The
Linux implementation of this interface may differ (consult the
corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
Имя (Name)
mbrtowc — convert a character to a wide-character code
(restartable)
Синопсис (Synopsis)
#include <wchar.h>
size_t mbrtowc(wchar_t *restrict pwc, const char *restrict s,
size_t n, mbstate_t *restrict ps);
Описание (Description)
The functionality described on this reference page is aligned
with the ISO C standard. Any conflict between the requirements
described here and the ISO C standard is unintentional. This
volume of POSIX.1‐2017 defers to the ISO C standard.
If s is a null pointer, the mbrtowc() function shall be
equivalent to the call:
mbrtowc(NULL, "", 1, ps)
In this case, the values of the arguments pwc and n are ignored.
If s is not a null pointer, the mbrtowc() function shall inspect
at most n bytes beginning at the byte pointed to by s to
determine the number of bytes needed to complete the next
character (including any shift sequences). If the function
determines that the next character is completed, it shall
determine the value of the corresponding wide character and then,
if pwc is not a null pointer, shall store that value in the
object pointed to by pwc. If the corresponding wide character is
the null wide character, the resulting state described shall be
the initial conversion state.
If ps is a null pointer, the mbrtowc() function shall use its own
internal mbstate_t object, which shall be initialized at program
start-up to the initial conversion state. Otherwise, the
mbstate_t object pointed to by ps shall be used to completely
describe the current conversion state of the associated character
sequence. The implementation shall behave as if no function
defined in this volume of POSIX.1‐2017 calls mbrtowc().
The behavior of this function is affected by the LC_CTYPE
category of the current locale.
The mbrtowc() function need not be thread-safe if called with a
NULL ps argument.
The mbrtowc() function shall not change the setting of errno if
successful.
Возвращаемое значение (Return value)
The mbrtowc() function shall return the first of the following
that applies:
0 If the next n or fewer bytes complete the character
that corresponds to the null wide character (which is
the value stored).
between 1 and n inclusive
If the next n or fewer bytes complete a valid
character (which is the value stored); the value
returned shall be the number of bytes that complete
the character.
(size_t)-2 If the next n bytes contribute to an incomplete but
potentially valid character, and all n bytes have
been processed (no value is stored). When n has at
least the value of the {MB_CUR_MAX} macro, this case
can only occur if s points at a sequence of redundant
shift sequences (for implementations with state-
dependent encodings).
(size_t)-1 If an encoding error occurs, in which case the next n
or fewer bytes do not contribute to a complete and
valid character (no value is stored). In this case,
[EILSEQ] shall be stored in errno and the conversion
state is undefined.
Ошибки (Error)
The mbrtowc() function shall fail if:
EILSEQ An invalid character sequence is detected. In the POSIX
locale an [EILSEQ] error cannot occur since all byte
values are valid characters.
The mbrtowc() function may fail if:
EINVAL ps points to an object that contains an invalid conversion
state.
The following sections are informative.
Примеры (Examples)
None.
Использование в приложениях (Application usage)
None.
Обоснование (Rationale)
None.
Будущие направления (Future directions)
None.
Смотри также (See also)
mbsinit(3p), mbsrtowcs(3p)
The Base Definitions volume of POSIX.1‐2017, wchar.h(0p)
