If dest is not a NULL pointer, the
function converts the
multibyte string *src to a wide-character string starting at dest.
At most len wide characters are written to dest.
The shift state
*ps is updated.
The conversion is effectively performed by repeatedly
mbrtowc(dest, *src, n, ps)
where n is some
positive number, as long as this call succeeds, and then incrementing
dest by one and *src by the number of bytes consumed.
The conversion can stop for three reasons:
An invalid multibyte sequence has been encountered.
In this case *src
is left pointing to the invalid multibyte sequence,
and errno is set to EILSEQ.
len non-L'\0' wide characters have been stored at dest.
case *src is left pointing to the next
multibyte sequence to be converted,
and the number of wide characters written to dest is returned.
The multibyte string has been completely converted, including the
terminating '\0' (which has the side
effect of bringing back *ps to the
In this case *src is set to NULL, and the number of wide
characters written to dest,
excluding the terminating L'\0' character, is returned.
If dest is NULL, len is ignored,
and the conversion proceeds as above,
except that the converted wide characters are not written out to memory,
and that no length limit exists.
In both of the above cases,
if ps is a NULL pointer, a static anonymous
state only known to the
function is used instead.
The programmer must ensure that there is room for at least len wide
characters at dest.
function returns the number of wide characters that make
up the converted part of the wide-character string, not including the
terminating null wide character.
If an invalid multibyte sequence was
is returned, and errno set to EILSEQ.
The behavior of
depends on the
category of the