WCRTOMB(3) Linux Programmer's Manual WCRTOMB(3)
wcrtomb - convert a wide character to a multibyte sequence
size_t wcrtomb(char *s, wchar_t wc, mbstate_t *ps);
The main case for this function is when s is not NULL and wc is not a null wide character
(L'\0'). In this case, the wcrtomb() function converts the wide character wc to its
multibyte representation and stores it at the beginning of the character array pointed to
by s. It updates the shift state *ps, and returns the length of said multibyte represen-
tation, that is, the number of bytes written at s.
A different case is when s is not NULL, but wc is a null wide character (L'\0'). In this
case the wcrtomb() function stores at the character array pointed to by s the shift
sequence needed to bring *ps back to the initial state, followed by a '\0' byte. It
updates the shift state *ps (i.e., brings it into the initial state), and returns the
length of the shift sequence plus one, that is, the number of bytes written at s.
A third case is when s is NULL. In this case wc is ignored, and the function effectively
wcrtomb(buf, L'\0', ps)
where buf is an internal anonymous buffer.
In all of the above cases, if ps is a NULL pointer, a static anonymous state known only to
the wcrtomb() function is used instead.
The wcrtomb() function returns the number of bytes that have been or would have been writ-
ten to the byte array at s. If wc can not be represented as a multibyte sequence (accord-
ing to the current locale), (size_t) -1 is returned, and errno set to EILSEQ.
The behavior of wcrtomb() depends on the LC_CTYPE category of the current locale.
Passing NULL as ps is not multithread safe.
This page is part of release 3.55 of the Linux man-pages project. A description of the
project, and information about reporting bugs, can be found at
GNU 2011-09-28 WCRTOMB(3)