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 Laq\0aq, it returns the number of bytes that were consumed
from s.
If the converted wide character is Laq\0aq, 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.
#include <this>
case the
mbrtowc()
function behaves as above, except 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.
If the conversion state represented by *ps denotes an
incomplete multibyte character conversion, the
mbrtowc()
function
returns (size_t) -1, sets errno to EILSEQ, and
leaves *ps in an undefined state.
Otherwise, 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.
Otherwise, *ps must be a valid mbstate_t object.
An mbstate_t object a can be initialized to the initial state
by zeroing it, for example using
memset(&a, 0, sizeof(a));
RETURN VALUE
The
mbrtowc()
function returns the number of bytes parsed from the
multibyte sequence starting at s, if a non-Laq\0aq wide character
was recognized.
It returns 0, if a Laq\0aq 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
C99.
NOTES
The behavior of
mbrtowc()
depends on the
LC_CTYPE
category of the
current locale.
This page is part of release 3.14 of the Linux
man-pages
project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.
