wcpncpy() is the wide-character equivalent of stpncpy(). It copies at most n wide characters from the wide-character string src, including the terminating L'\0' character, to the array dest. Exactly n wide characters are written at dest. If the length wcslen()(src) is smaller than n, the remaining wide characters in the array dest are filled with L'\0' characters. If the length wcslen()(src) is greater than or equal to n, the string dest will not be L'\0' terminated.
The strings may not overlap.
The programmer shall ensure that there is room for at least n wide characters at dest.
wcpncpy() returns a pointer to the wide character one past the last non-null wide character written.