Question

I want to write some macro specific to Excel 64 bit.,
the below link says about a macro,
http://msdn.microsoft.com/en-us/library/office/gg264421.aspx

But it says “#if Win64” : Whether it reffers excatly office version..? because Users can install Office 32 bit 2010 in Windows 64 bit OS.

Answer 1

But it says “#if Win64” : Whether it reffers excatly office version..?
because Users can install Office 32 bit 2010 in Windows 64 bit OS.

The Win64 constant used within a #If…then…#Else is a compiler constant. If it returns true, it indicates that the development environment is 64-bit compatible. Which means code written for a 32-bit environment may have issues.

In general the only conflict you may encounter between 32 bit VBA and 64 bit VBA is if you attempt to call outside Dlls via Declare. As described in the link you provided, the primary potential issue is this:

The problem with running legacy VBA code in 64-bit Office is that
trying to load 64-bits into a 32-bit data type truncates the 64-bit
quantity. This can result in memory overruns, unexpected results in
your code, and possible application failure.

Probably your legacy code would still work, but you make the adjustment to assure that it will work.

The method of handling this is described in the link you provided where you provide the correct calling method for 64-bit within the #If…then…#Else structure using the compiler constants.