wcsncat - concatenate two wide-character strings
wchar_t *wcsncat(wchar_t *dest, const wchar_t *src, size_t n);
The wcsncat() function is the wide-character equivalent of the strncat(3) function. It copies at most n wide characters from the wide-character string pointed to by src to the end of the wide-character string pointed to by dest, and adds a terminating null wide character (L\(aq\0\(aq).
The strings may not overlap.
The programmer must ensure that there is room for at least wcslen(dest)+n+1 wide characters at dest.
wcsncat() returns dest.
For an explanation of the terms used in this section, see attributes(7).
POSIX.1-2001, POSIX.1-2008, C99.