wcsnrtombs -- convert a wide character string to a multi-byte string


#include <wchar.h>

size_t wcsnrtombs(char * dest, const wchar_t * * src, size_t nwc, size_t len, mbstate_t * ps);


wcsnrtombs() is like wcsrtombs(), except that the number of wide characters to be converted, starting at src, is limited to nwc.

If dest is not a NULL pointer, wcsnrtombs() converts at most nwc wide characters from the wide-character string src to a multibyte string starting at dest. At most len bytes are written to dest. The shift state ps is updated.

The conversion is effectively performed by repeatedly calling:

wcrtomb(dest, *src, ps)
as long as this call succeeds, and then incrementing dest by the number of bytes written and src by 1.

The conversion can stop for three reasons:

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 destination length limit exists.

In both of the above cases, if ps is a NULL pointer, a static anonymous state only known to wcsnrtombs() is used instead.

The programmer shall ensure that there is room for at least len bytes at dest.

Return Value

wcsnrtombs() returns the number of bytes that make up the converted part of multibyte sequence, not including the terminating null wide character code. If a wide character was encountered which could not be converted, (size_t)(-1) is returned, and the global variable errno set to EILSEQ.


The behavior of wcsnrtombs() depends on the LC_CTYPE category of the current locale.

Passing NULL as ps is not multi-thread safe.