size_t wcsrtombs(char *restrict dst, const wchar_t **restrict
size_t len, mbstate_t *restrict ps);
The wcsrtombs() function shall convert a sequence of wide characters from the array indirectly pointed to by src into a sequence of corresponding characters, beginning in the conversion state described by the object pointed to by ps. If dst is not a null pointer, the converted characters shall then be stored into the array pointed to by dst. Conversion continues up to and including a terminating null wide character, which shall also be stored. Conversion shall stop earlier in the following cases:
Each conversion shall take place as if by a call to the wcrtomb() function.
If dst is not a null pointer, the pointer object pointed to by src shall be assigned either a null pointer (if conversion stopped due to reaching a terminating null wide character) or the address just past the last wide character converted (if any). If conversion stopped due to reaching a terminating null wide character, the resulting state described shall be the initial conversion state.
If ps is a null pointer, the wcsrtombs() function shall use its own internal mbstate_t object, which is initialized at program start-up to the initial conversion state. Otherwise, the mbstate_t object pointed to by ps shall be used to completely describe the current conversion state of the associated character sequence. The implementation shall behave as if no function defined in this volume of IEEE Std 1003.1-2001 calls wcsrtombs().
If the application uses any of the _POSIX_THREAD_SAFE_FUNCTIONS or _POSIX_THREADS functions, the application shall ensure that the wcsrtombs() function is called with a non-NULL ps argument.
The behavior of this function shall be affected by the LC_CTYPE category of the current locale.
If conversion stops because a code is reached that does not correspond to a valid character, an encoding error occurs. In this case, the wcsrtombs() function shall store the value of the macro [EILSEQ] in errno and return (size_t)-1; the conversion state is undefined. Otherwise, it shall return the number of bytes in the resulting character sequence, not including the terminating null (if any).
The wcsrtombs() function may fail if:
The following sections are informative.
mbsinit() , wcrtomb() , the Base Definitions volume of IEEE Std 1003.1-2001, <wchar.h>