If dest is not a NULL pointer,
the wide-character string *src to a multibyte string starting at
At most len bytes are written to dest.
The shift state
*ps is updated.
The conversion is effectively performed by repeatedly
wcrtomb(dest, *src, ps),
as long as this call succeeds,
and then incrementing dest by the
number of bytes written and *src
The conversion can stop for three reasons:
1. A wide character has been encountered that can not be represented as a
multibyte sequence (according to the current locale).
In this case *src
is left pointing to the invalid wide character,
is set to EILSEQ.
2. The length limit forces a stop.
In this case *src is left pointing
to the next wide character to be converted,
and the number of bytes written to
dest is returned.
3. The wide-character string has been completely converted, including the
terminating L'\0' (which has the side effect of bringing back *ps
to the initial state).
In this case *src is set to NULL, and the number
of bytes written to dest, excluding the terminating '\0' byte, is
If dest is NULL, len is ignored,
and the conversion proceeds as above, except that the converted bytes
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 wcsrtombs function is used instead.
The programmer must ensure that there is room for at least len bytes
the number of bytes that make up the
converted part of multibyte sequence,
not including the terminating null byte.
If a wide character was encountered
which could not be converted,
is returned, and
set to EILSEQ.
The behavior of
depends on the
category of the