The wcsncpy function is the wide-character equivalent of the
strncpy function. It copies at most n wide characters from the
wide-character string pointed to by src, including the terminating
L'\0' character, to the array pointed to by 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 pointed to
by dest are filled with L'\0' characters. If the length
wcslen(src) is greater or equal to n, the string pointed to by
dest will not be L'\0' terminated.
The strings may not overlap.
The programmer must ensure that there is room for at least n wide
characters at dest.