получить количество байтов в символе (get number of bytes in a character)
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)
mblen — get number of bytes in a character
Синопсис (Synopsis)
#include <stdlib.h>
int mblen(const char *s, size_t n);
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 not a null pointer, mblen() shall determine the number of
bytes constituting the character pointed to by s. Except that
the shift state of mbtowc() is not affected, it shall be
equivalent to:
mbtowc((wchar_t *)0, s, n);
The implementation shall behave as if no function defined in this
volume of POSIX.1‐2017 calls mblen().
The behavior of this function is affected by the LC_CTYPE
category of the current locale. For a state-dependent encoding,
this function shall be placed into its initial state by a call
for which its character pointer argument, s, is a null pointer.
Subsequent calls with s as other than a null pointer shall cause
the internal state of the function to be altered as necessary. A
call with s as a null pointer shall cause this function to return
a non-zero value if encodings have state dependency, and 0
otherwise. If the implementation employs special bytes to change
the shift state, these bytes shall not produce separate wide-
character codes, but shall be grouped with an adjacent character.
Changing the LC_CTYPE category causes the shift state of this
function to be unspecified.
The mblen() function need not be thread-safe.
Возвращаемое значение (Return value)
If s is a null pointer, mblen() shall return a non-zero or 0
value, if character encodings, respectively, do or do not have
state-dependent encodings. If s is not a null pointer, mblen()
shall either return 0 (if s points to the null byte), or return
the number of bytes that constitute the character (if the next n
or fewer bytes form a valid character), or return -1 (if they do
not form a valid character) and may set errno to indicate the
error. In no case shall the value returned be greater than n or
the value of the {MB_CUR_MAX} macro.
Ошибки (Error)
The mblen() function may 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 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)
mbtowc(3p), mbstowcs(3p), wctomb(3p), wcstombs(3p)
The Base Definitions volume of POSIX.1‐2017, stdlib.h(0p)
