Problem with C++ DLLs

Question

Hello.
How can I send an array to a function in a dll that in writed with C++ ? In dll, function prototype syntax should be in C# or C/C++ ?
in dll, can I declare global variables ? If yes, declare them with C# syntax or C/C++ syntax ?

I want to write dll in Borland C++. Can it create Problem ?

Excuse me for bad english and too many questions.
Thanks :-)