NAME¶
mbrtowc - convert a multibyte sequence to a wide character
SYNOPSIS¶
#include <wchar.h>
size_t mbrtowc (wchar_t *pwc, const char *s, size_t n, mbstate_t *ps);
DESCRIPTION¶
The main case for this function is when
s is not NULL and
pwc is
not NULL. In this case, the
mbrtowc function inspects at most
n
bytes of the multibyte string starting at
s, extracts the next complete
multibyte character, converts it to a wide character and stores it at
*pwc. It updates the shift state
*ps. If the converted wide
character is not L'\0', it returns the number of bytes that were consumed from
s. If the converted wide character is L'\0', it resets the shift state
*ps to the initial state and returns 0.
If the
n bytes starting at
s do not contain a complete multibyte
character,
mbrtowc returns
(size_t)(-2). This can happen even if
n >=
MB_CUR_MAX, if the multibyte string contains redundant
shift sequences.
If the multibyte string starting at
s contains an invalid multibyte
sequence before the next complete character,
mbrtowc returns
(size_t)(-1) and sets
errno to
EILSEQ. In this case, the
effects on
*ps are undefined.
A different case is when
s is not NULL but
pwc is NULL. In this
case the
mbrtowc function behaves as above, excepts that it does not
store the converted wide character in memory.
A third case is when
s is NULL. In this case,
pwc and
n are
ignored. The
mbrtowc function puts
*ps in the initial state and
returns 0.
In all of the above cases, if
ps is a NULL pointer, a static anonymous
state only known to the mbrtowc function is used instead.
RETURN VALUE¶
The
mbrtowc function returns the number of bytes parsed from the
multibyte sequence starting at
s, if a non-L'\0' wide character was
recognized. It returns 0, if a L'\0' wide character was recognized. It returns
(size_t)(-1) and sets
errno to
EILSEQ, if an invalid multibyte
sequence was encountered. It returns (size_t)(-2) if it couldn't parse a
complete multibyte character, meaning that
n should be increased.
ISO/ANSI C, UNIX98
SEE ALSO¶
mbsrtowcs(3)
NOTES¶
The behaviour of
mbrtowc depends on the LC_CTYPE category of the current
locale.