#include <wchar.h> size_t wcsrtombs(char *restrict dst, const wchar_t **restrict src, size_t len, mbstate_t *restrict ps);
The wcsrtombs() function converts 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 are then stored into the array pointed to by dst. Conversion continues up to and including a terminating null wide-character, which is also stored. Conversion stops earlier in the following cases:
When a code is reached that does not correspond to a valid character.
When the next character would exceed the limit of len total bytes to be stored in the array pointed to by dst (and dst is not a null pointer).
Each conversion takes place as if by a call to the wcrtomb() function.
If dst is not a null pointer, the pointer object pointed to by src is 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 is the initial conversion state.
If ps is a null pointer, the wcsrtombs() function uses its own internal mbstate_t object, which is initialized at program startup to the initial conversion state. Otherwise, the mbstate_t object pointed to by ps is used to completely describe the current conversion state of the associated character sequence. Solaris will behave as if no function defined in the Solaris Reference Manual calls wcsrtombs().
The behavior of this function is affected by the LC_CTYPE category of the current locale. See environ(5).
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 stores the value of the macro EILSEQ in errno and returns (size_t)−1 ; the conversion state is undefined. Otherwise, it returns the number of bytes in the resulting character sequence, not including the terminating null (if any).
The wcsrtombs() function may fail if:
The ps argument points to an object that contains an invalid conversion state.
A wide-character code does not correspond to a valid character.
If ps is not a null pointer, wcsrtombs() uses the mbstate_t object pointed to by ps and the function can be used safely in multithreaded applications, as long as setlocale(3C) is not being called to change the locale. If ps is a null pointer, wcsrtombs() uses its internal mbstate_t object and the function is Unsafe in multithreaded applications.
See attributes(5) for descriptions of the following attributes: