How should I make my VBA code compatible with 64-bit Windows?

I've already encountered this problem on people using my in-house tools on new 64 bit machines with Office 2010.

all I had to do was change lines of code like this:

Private Declare Function ShellExecute Lib "shell32.dll" Alias "ShellExecuteA" _    (ByVal hwnd As Long, ByVal lpOperation As String, ByVal lpFile As String, ByVal lpParameters As String, ByVal lpDirectory As String, ByVal nShowCmd As Long) As Long

To This:

#If VBA7 Then    Private Declare PtrSafe Function ShellExecute Lib "shell32.dll" Alias "ShellExecuteA" _        (ByVal hwnd As Long, ByVal lpOperation As String, ByVal lpFile As String, ByVal lpParameters As String, ByVal lpDirectory As String, ByVal nShowCmd As Long) As Long#Else    Private Declare Function ShellExecute Lib "shell32.dll" Alias "ShellExecuteA" _        (ByVal hwnd As Long, ByVal lpOperation As String, ByVal lpFile As String, ByVal lpParameters As String, ByVal lpDirectory As String, ByVal nShowCmd As Long) As Long#End If

You will, of course want to make sure that the library you're using is available on both machines, but so far nothing I've used has been a problem.

Note that in the old VB6, PtrSafe isn't even a valid command, so it'll appear in red as though you have a compile error, but it won't actually ever give an error because the compiler will skip the first part of the if block.

Applications using the above code compile and run perfectly on Office 2003, 2007, and 2010 32 and 64 bit.

Office 2007 is 32 bit only so there is no issue there. Your problems arise only with Office 64 bit which has both 32 and 64 bit versions.

You cannot hope to support users with 64 bit Office 2010 when you only have Office 2007. The solution is to upgrade.

If the only Declare that you have is that ShellExecute then you won't have much to do once you get hold of 64 bit Office, but it's not really viable to support users when you can't run the program that you ship! Just think what you would do you do when they report a bug?

i found this code (note that some Long are changed to LongPtr):

Declare PtrSafe Function ShellExecute Lib "shell32.dll" _Alias "ShellExecuteA" (ByVal hwnd As LongPtr, ByVal lpOperation As String, _ByVal lpFile As String, ByVal lpParameters As String, ByVal lpDirectory As _String, ByVal nShowCmd As Long) As LongPtr

source: http://www.cadsharp.com/docs/Win32API_PtrSafe.txt