wchar_t *wmemchr(const wchar_t *s, wchar_t c, size_t n);
wmemchr locates the first occurrence of c in the initial n characters of the object pointed to by s. Unlike wcschr, wmemchr does not terminate a search when a null wide character is found in the object pointed to by s.
wmemchr returns a pointer to the located wide character, or a null pointer if c does not occur in the object.