#include <wchar.h> size_t mbsnrtowcs(wchar_t *restrict dst, const char **restrict src, size_t nmc, size_t len, mbstate_t *restrict ps); size_t mbsrtowcs(wchar_t *restrict dst, const char **restrict src, size_t len, mbstate_t *restrict ps);
The mbsrtowcs() function shall convert a sequence of characters, beginning in the conversion state described by the object pointed to by ps, from the array indirectly pointed to by src into a sequence of corresponding wide characters. If dst is not a null pointer, the converted characters shall be stored into the array pointed to by dst. Conversion continues up to and including a terminating null character, which shall also be stored. Conversion shall stop early in either of the following cases:
Each conversion shall take place as if by a call to the mbrtowc() 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 character) or the address just past the last character converted (if any). If conversion stopped due to reaching a terminating null character, and if dst is not a null pointer, the resulting state described shall be the initial conversion state.
If ps is a null pointer, the mbsrtowcs() 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 mbsnrtowcs() function shall be equivalent to the mbsrtowcs() function, except that the conversion of characters indirectly pointed to by src is limited to at most nmc bytes (the size of the input buffer), and under conditions where mbsrtowcs() would assign the address just past the last character converted (if any) to the pointer object pointed to by src, mbsnrtowcs() shall instead assign the address just past the last byte processed (if any) to that pointer object. If the input buffer ends with an incomplete character, it is unspecified whether conversion stops at the end of the previous character (if any), or at the end of the input buffer. In the latter case, a subsequent call to mbsnrtowcs() with an input buffer that starts with the remainder of the incomplete character shall correctly complete the conversion of that character.
The behavior of these functions shall be affected by the LC_CTYPE category of the current locale.
The implementation shall behave as if no function defined in this volume of POSIX.1-2017 calls these functions.
The mbsnrtowcs() and mbsrtowcs() functions need not be thread-safe if called with a NULL ps argument.
These functions may fail if:
The Base Definitions volume of POSIX.1-2017, <wchar.h>
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