XL97: "Bad DLL Calling Convention" When Running a Macro

When you run a Visual Basic for Applications macro in Microsoft Excel 97, you may receive the following error message:

This problem may occur when all of the following conditions are true:

• The Visual Basic macro code contains one or more Declare Function statements.
  
  -and-
• One of the Declare Function statements refers to a function in a dynamic-link library file (DLL) that uses the _cdecl calling convention.
  
  -and-
• Within the code, you make a call to the declared function.

In Microsoft Excel 97, Visual Basic macros can only call functions that use the _stdcall calling convention. Functions that use the _cdecl calling convention are not supported.

DLLs in Microsoft Windows support two main calling conventions: _cdecl and _stdcall. Most 32-bit DLLs that are included with Microsoft Windows 95 and Microsoft Windows NT support the _stdcall calling convention; the _cdecl calling convention is generally used by older DLLs.

If a DLL supports only the _cdecl calling convention, you cannot call functions in that DLL from a Visual Basic macro in Microsoft Excel 97. For example, if your code includes the following function declaration: and then attempts to call the memcpy& function, you will receive the error message described in this article. This behavior occurs because macros in Microsoft Excel 97 cannot call functions that use the _cdecl calling convention.

NOTE: In earlier versions of Microsoft Excel, you can make calls to functions that use the _cdecl calling convention.