The Microsoft Office 2010 system is available in both 32-bit and 64-bit versions. The 64-bit version enables you to work with much larger sets of data. This need is especially true when working with large numbers in Microsoft Excel 2010.

With the introduction of the new 64-bit version of Microsoft Office 2010, a new version of Microsoft Visual Basic for Applications (VBA), known as Microsoft Visual Basic for Applications 7.0 (VBA 7), is being released to work with both 32-bit and 64-bit applications. It is important to note that the changes addressed in this article apply only to the 64-bit version of Microsoft Office 2010. Using the 32-bit version of Office 2010 enables you to use solutions built in previous versions of Microsoft Office without modification.

Note:
In a default installation of Office 2010, the 32-bit version is installed, even on 64-bit systems. You must explicitly select the Office 2010 64-bit version installation option.

In VBA 7, you must update existing Windows Application Programming Interface (API) statements (Declare statements) to work with the 64-bit version. Additionally, you must update address pointers and display window handles in user-defined types that are used by these statements. This is discussed in more detail in this article as well as compatibility issues between the 32-bit and 64-bit versions of Office 2010 and suggested solutions.

Applications built with the 64-bit version of Office 2010 can reference larger address spaces, and therefore provide the opportunity to use more physical memory than ever, potentially reducing the overhead spent moving data in and out of physical memory.

In addition to referring to specific locations (also known as pointers) in physical memory that an application uses to store data or to store programming instructions, you can also use addresses to reference display window identifiers (known as handles). Depending on whether you are using a 32-bit or 64-bit system determines the size (in bytes) of the pointer or handle.

There are two fundamental issues when you run existing solutions with the 64-bit version of Office 2010:

• Native 64-bit processes in Office 2010 cannot load 32-bit binaries. This is expected to be a common issue when you have existing Microsoft ActiveX controls and existing add-ins,
  
  
• VBA previously did not have a pointer data type and because of this, developers used 32-bit variables to store pointers and handles. These variables now truncate 64-bit values returned by API calls when using Declare statements.
  
  

VBA 7 is a new code base, replacing the earlier version of VBA. VBA 7 exists for both the 32-bit and 64-bit versions of Office 2010. It provides two conditional compilation constants: VBA7 and Win64. The VBA7 constant helps ensure the backward compatibility of your code by testing whether your application is using VBA 7 or the previous version of VBA. The Win64 constant is used to test whether code is running as 32-bit or as 64-bit. Both of these compilation constants are demonstrated later in this article.

With certain exceptions shown elsewhere in this article, the macros in a document (this also includes workbook and presentations) that have worked by using the 32-bit version of that application will work when the document is loaded in the 64-bit version of the same application.

Existing 32-bit ActiveX controls, both third-party and Microsoft-supplied, are not compatible with the 64-bit version of Office 2010. For ActiveX controls and COM objects, there are three possible solutions:

• If you have the source code, you can generate a 64-bit version yourself,
  
  
• You can contact the vendor for an updated version,
  
  
• You can search for an alternative solution.
  
  

Native 64-bit processes in Office 2010 cannot load 32-bit binaries. This includes the common controls of MSComCtl (TabStrip, Toolbar, StatusBar, ProgressBar, TreeView, ListViews, ImageList, Slider, ImageComboBox) and the controls of MSComCt2 (Animation, UpDown, MonthView, DateTimePicker, FlatScrollBar).These controls were installed by previous versions of Microsoft Office and are installed by 32-bit Office 2010. An alternative must be found for existing Microsoft Office VBA solutions that utilize these controls when the code is migrated to 64-bit Office 2010. 64-bit Office 2010 does not provide 64-bit versions of the Common Controls.

The combination of VBA and type libraries gives you lots of functionality to create Microsoft Office applications. However, sometimes you must communicate directly with the computer’s operating system and other components such as when you manage memory or processes, when working with the user interface such as windows and controls, or when modifying the Windows registry. In these scenarios, your best option is to use one of the external functions that are embedded in dynamic linked library (DLL) files. You do this in VBA by making API calls using Declare statements.

Note:

Microsoft provides a Win32API.txt file which contains 1,500 Declare statements and a tool to cut and paste the Declare statement that that you want into your code. However, these statements are for 32-bit systems and must be converted to 64-bit by using the information discussed later in this article. Existing Declare statements will not compile in 64-bit VBA until they have been marked as safe for 64-bit by using the PtrSafe attribute. You can find samples of this type of conversion at Excel MVP Jan Karel Pieterse’s Web site at: http://www.jkp-ads.com/articles/apideclarations.asp. The Office Code Compatibility Inspector user’s guide is a useful tool to inspect the syntax of API Declare statements for the PtrSafe attribute, if needed, and the appropriate return type.

Declare statements resemble one of the following, depending whether you are calling a subroutine (which has no return value) or a function (which does have a return value).

Public/Private Declare Sub SubName Lib "LibName" Alias "AliasName" (argument list)
Public/Private Declare Function FunctionName Lib "Libname" alias "aliasname" (argument list) As Type

The SubName function or FunctionName function is replaced by the actual name of the procedure in the DLL file and represents the name that is used when the procedure is called from VBA code. You can also specify an AliasName argument for the name of the procedure, if desired. The name of the DLL file that contains the procedure being called follows the Lib keyword. And finally, the argument list contains the parameters and the data types that must be passed to the procedure.

The following Declare statement opens a subkey in the Windows registry and replaces its value.

Declare Function RegOpenKeyA Lib "advapi32.dll" (ByVal Key As Long, ByVal SubKey As String, NewKey As Long) As Long

The Windows.h (window handle) entry for the RegOpenKeyA function is as follows:

LONG RegOpenKeyA ( HKEY hKey, LPCSTR lpSubKey, HKEY *phkResult );

In Microsoft Visual C and Microsoft Visual C++, the previous example compiles correctly for both 32-bit and 64-bit. This is because HKEY is defined as a pointer, whose size reflects the memory size of the platform that the code is compiled in.

In previous versions of VBA, there was no specific pointer data type so the Long data type was used. And because the Long data type is always 32-bits, this breaks when used on a system with 64-bit memory because the upper 32-bits may be truncated or may overwrite other memory addresses. Either of these situations can result in unpredictable behavior or system crashes.

To resolve this, VBA now contains a true pointer data type: LongPtr. This new data type enables you to write the original Declare statement correctly as:

Declare PtrSafe Function RegOpenKeyA Lib “advapire32.dll” (ByVal hKey as LongPtr, ByVal lpSubKey As String, phkResult As LongPtr) As Long

This data type and the new PtrSafe attribute enable you to use this Declare statement on either 32-bit or 64-bit systems. The PtrSafe attribute indicates to the VBA compiler that the Declare statement is targeted for the 64-bit version of Office 2010. Without this attribute, using the Declare statement in a 64-bit system will result in a compile-time error. Note that the PtrSafe attribute is optional on the 32-bit version of Office 2010. This enables existing Declare statements to work as they always have.

The following table provides more information on the new qualifier and data type already discussed as well as another data type, two conversion operators, and three functions.

The follow example shows how to use some of these items in a Declare statement.

Declare PtrSafe Function RegOpenKeyA Lib "advapi32.dll" (ByVal Key As LongPtr, ByVal SubKey As String, NewKey As LongPtr) As Long

Note that Declare statements without the PtrSafe attribute are assumed not to be compatible with the 64-bit version of Office 2010.

As stated earlier, there are two new conditional compilation constants: VBA7 and Win64. To ensure backward compatibility with previous versions of Microsoft Office, you use the VBA7 constant (this is the more typical case) to prevent 64-bit code from being used in the earlier version of Microsoft Office. For code that is different between the 32-bit version and the 64-bit version, such as calling a math API which uses LongLong for its 64-bit version and Long for its 32-bit version, you use the Win64 constant. The following code demonstrates the use of these two constants.

#if Win64 then
   Declare PtrSafe Function MyMathFunc Lib "User32" (ByVal N As LongLong) As LongLong
#else
   Declare Function MyMathFunc Lib "User32" (ByVal N As Long) As Long
#end if
#if VBA7 then
   Declare PtrSafe Sub MessageBeep Lib "User32" (ByVal N AS Long)
#else
   Declare Sub MessageBeep Lib "User32" (ByVal N AS Long)
#end if

To summarize, if you write 64-bit code and intend to use it in previous versions of Microsoft Office, you will want to use the VBA7 conditional compilation constant. However, if you write 32-bit code in Office 2010, that code works as is in previous versions of Microsoft Office without the need for the compilation constant. If you want to ensure that you are using 32-bit statements for 32-bit versions and 64-bit statements for 64-bit versions, your best option is to use the Win64 conditional compilation constant.

The following code is an example of legacy VBA code that needs to be updated. Notice the data types in the legacy code that are updated to use LongPtr because they refer to handles or pointers

Legacy VBA Code

Declare Function SHBrowseForFolder Lib "shell32.dll" _
  Alias "SHBrowseForFolderA" (lpBrowseInfo As BROWSEINFO) As Long
  
Public Type BROWSEINFO
  hOwner As Long
  pidlRoot As Long
  pszDisplayName As String
  lpszTitle As String
  ulFlags As Long
  lpfn As Long
  lParam As Long
  iImage As Long
End Type

New VBA Code

#if VBA7 then    ' VBA7 
Declare PtrSafe Function SHBrowseForFolder Lib "shell32.dll" _
  Alias "SHBrowseForFolderA" (lpBrowseInfo As BROWSEINFO) As Long

Public Type BROWSEINFO
  hOwner As LongPtr
  pidlRoot As Long
  pszDisplayName As String
  lpszTitle As String
  ulFlags As Long
  lpfn As LongPtr
  lParam As LongPtr
  iImage As Long
End Type
 
#else    ' Downlevel when using previous version of VBA7

Declare Function SHBrowseForFolder Lib "shell32.dll" _
  Alias "SHBrowseForFolderA" (lpBrowseInfo As BROWSEINFO) As Long

Public Type BROWSEINFO
  hOwner As Long
  pidlRoot As Long
  pszDisplayName As String
  lpszTitle As String
  ulFlags As Long
  lpfn As Long
  lParam As Long
  iImage As Long
End Type
 
#end if
Sub TestSHBrowseForFolder ()
    Dim bInfo As BROWSEINFO
    Dim pidList As Long

    bInfo.pidlRoot = 0&
    bInfo.ulFlags = &H1
    pidList = SHBrowseForFolder(bInfo)
End Sub

The following are frequently asked questions that relate to the 32-bit and 64-bit versions of Microsoft Office.

When should I use the 64-bit version of Microsoft Office?

This is more a matter of which host application (Excel, Word, and so forth) you are using. For example, Excel is able to handle much larger worksheets with the 64-bit version of Microsoft Office.

Can I install 64-bit and 32-bit versions of Microsoft Office side-by-side?

No.

When should I convert Long parameters to LongPtr?

You need to check the Windows API documentation on the Microsoft Developers Network for the function you want to call. Handles and pointers need to be converted to LongPtr. As an example, the documentation for RegOpenKeyA provides the following signature:

C#

LONG WINAPI RegOpenKeyEx(
  __in        HKEY hKey,
  __in_opt    LPCTSTR lpSubKey,
  __reserved  DWORD ulOptions,
  __in        REGSAM samDesired,
  __out       PHKEY phkResult
);

The parameters are defined as:

 

Parameter	Description
hKey [in]	A handle to an open registry key.
lpSubKey [in, optional]	The name of the registry subkey to be opened.
ulOptions	This parameter is reserved and must be zero.
samDesired [in]	A mask that specifies the desired access rights to the key.
phkResult [out]	A pointer to a variable that receives a handle to the opened key.

In Win32API_PtrSafe.txt, the Declare statement is defined as:

Declare PtrSafe Function RegOpenKeyEx Lib "advapi32.dll" Alias "RegOpenKeyExA" (ByVal hKey As LongPtr, ByVal lpSubKey As String, ByVal ulOptions As Long, ByVal samDesired As Long, phkResult As LongPtr) As Long

Should I convert pointers and handles in structures?

Yes. See the MSG type in Win32API_PtrSafe.txt:

Type MSG
    hwnd As LongPtr
    message As Long
    wParam As LongPtr
    lParam As LongPtr
    time As Long
    pt As POINTAPI
End TypeF

When should I use strptr, varpt, and objptr?

You should use these functions to retrieve pointers to strings, variables and objects, respectively. On the 64-bit version of Microsoft Office, these functions will return a 64-bit LongPtr, which can be passed to Declare statements. The use of these functions has not changed from previous versions of VBA. The only difference is that they now return a LongPtr.

The addition of a 64-bit version of Office 2010 enables you to move more data around for increased capability. When writing 32-bit code, you can use the 64-bit version of Microsoft Office without any changes. However, when you write 64-bit code, you should ensure that your code contains specific keywords and conditional compilation constants to ensure that the code is backward compatible with earlier version of Microsoft Office, and that the correct code is being executed if you mix 32-bit and 64-bit code.

For more information about Declare statements, see the following resources:

• Anatomy of a Declare Statement