When I registered dao350.dll with regsvr32 and tried opening Visual Basic, it gave me an error: "Unexpected error; quitting"<BR><BR>I don't have the original installation disks, so I can't reinstall.

For Visual Basic applications (or applications in other languages such as Pascal or Fortran) to call functions in a C/C++ DLL, the functions must be exported using the correct calling convention ...

You probably need to declare area() as PASCAL calling convention and with the EXPORT macro so that it is, indeed, exported from your DLL. You'll also have to defeat C++ "name-mangling", so define it ...

Declares a reference to a procedure implemented in an external file. name Required. Name of this external reference. For more information, see Declared Element Names. Lib Required. Introduces a Lib ...

A version of BASIC from Microsoft specialized for Windows. A subset of Visual Basic provides a macro language for Microsoft applications (see VBA). When released in 1991, Visual Basic (VB) was similar ...