MBRTOWC (3)
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.
CONFORMING TO
SEE ALSO
NOTES
The behaviour of mbrtowc depends on the LC_CTYPE category of the
current locale.
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