That's because VFP cannot pass arrays to DLL functions as well as it cannot pass structures.
But you can create a string buffer of the same length, fill it with a C-style data and pass it to the DLL function.
See "Accessing Dynamic-Link Libraries" in VFP documantation.
/A new technology turns into completely outdated stuff before you have a time to read "Getting Started..." section.
/If there are some "system programmers" then others are unsystematic.