Concatenates a string of a specified length after another string.
wchar_t *wcsncat(wchar_t * restrict s1, const wchar_t * restrict s2, size_t n);
s1 Pointer to the string after which another string is appended
s2 Pointer to the string to be appended after the other string
n Number of characters to concatenate
The wcsncat function is the wide-character version of the strncat function.