libwchar2 0.0.10
|
mbrtowc - convert a multibyte sequence to a wide characte
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' (the null wide character), 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, 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 NULL
, a static anonymous state known only 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:
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.
The behavior of mbrtowc() depends on the LC_CTYPE
category of the current locale.