Compatibility between the 32-bit and 64-bit versions of Office

Article
03/31/2022

Find out how the 32-bit version of Office is compatible with the 64-bit version of Office.

Office applications are available in 32-bit and 64-bit versions.

The 64-bit versions of Office enable you to move more data around for increased capability, for example when you work with large numbers in Microsoft Excel 2010. When writing 32-bit code, you can use the 64-bit version of 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 Office, and that the correct code is being executed if you mix 32-bit and 64-bit code.

Visual Basic for Applications 7.0 (VBA 7) is released in the 64-bit versions for Office, and it works with both 32-bit and 64-bit applications. The changes described in this article apply only to the 64-bit versions of Office. Using the 32-bit versions of Microsoft Office enable you to use solutions built in previous versions of Office without further modifications.

Note

By default, when you install a 64-bit version of Office you cannot install the 32-bit version alongside it. You must explicitly select the Microsoft Office 64-bit version installation option.

In VBA 7, you must update existing Windows 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 and suggested solutions.

Comparing 32-bit and 64-bit systems

Applications built with the 64-bit versions of Office can reference larger address spaces than 32-bit versions. This means you can use more physical memory for data than before, potentially reducing the overhead spent moving data in and out of physical memory

In addition to referring specific locations (known as pointers) in physical memory, you can also use addresses to reference display window identifiers (known as handles). The size (in bytes) of the pointer or handle depends on whether you're using a 32-bit or 64-bit system.

If you want to run your existing solutions with the 64-bit versions of Office, be aware of the following:

Native 64-bit processes in Office 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 didn't have a pointer data type, so you had to use 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 code base

VBA 7 replaces the VBA code base in Office 2007 and earlier versions. VBA 7 is available in both the 32-bit and 64-bit versions of Office. It provides two conditional compilation constants:

VBA7 - Helps ensure the backward compatibility of your code by testing whether your application is using VBA 7 or the previous version of VBA.
Win64 Tests whether code is running as 32-bit or 64-bit.

With certain exceptions, the macros in a document that work in the 32-bit version of the application also work in the 64-bit version.

ActiveX control and COM add-in compatibility

Existing 32-bit ActiveX controls, are not compatible with the 64-bit versions of Office. For ActiveX controls and COM objects:

If you have the source code, generate a 64-bit version yourself.
If you don't have the source code, contact the vendor for an updated version.

Native 64-bit processes in Office 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 32-bit versions of Office earlier than Office 2010. You'll need to find an alternative for your existing VBA solutions that use these controls when you migrate the code to the 64-bit versions of Office.

API compatibility

The combination of VBA and type libraries gives you lots of functionality to create 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 UI elements linke 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 DLL files. You do this in VBA by making API calls using Declare statements.

Note

Microsoft provides a Win32API.txt file that contains 1,500 Declare statements and a tool to copy the Declare statement 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 won't compile in 64-bit VBA until they've been marked as safe for 64-bit by using the PtrSafe attribute. You can find examples of this type of conversion at Excel MVP Jan Karel Pieterse's website at https://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 on 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. 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 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 might be truncated or might overwrite other memory addresses. Either of these situations can result in unpredictable behavior or system crashes.

To resolve this, VBA includes 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. Without this attribute, using the Declare statement in a 64-bit system will result in a compile-time error. The PtrSafe attribute is optional on the 32-bit version of Office. This enables existing Declare statements to work as they always have.

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

Type	Item	Description
Qualifier	PtrSafe	Indicates that the Declare statement is compatible with 64-bits. This attribute is mandatory on 64-bit systems.
Data Type	LongPtr	A variable data type which is a 4-bytes data type on 32-bit versions and an 8-byte data type on 64-bit versions of Microsoft Office. This is the recommended way of declaring a pointer or a handle for new code but also for legacy code if it has to run in the 64-bit version of Office. It is only supported in the VBA 7 runtime on 32-bit and 64-bit. Note that you can assign numeric values to it but not numeric types.
Data Type	LongLong	This is an 8-byte data type which is available only in 64-bit versions of Microsoft Office. You can assign numeric values but not numeric types (to avoid truncation).
Conversion Operator	CLngPtr	Converts a simple expression to a LongPtr data type.
Conversion Operator	CLngLng	Converts a simple expression to a LongLong data type.
Function	VarPtr	Variant converter. Returns a LongPtr on 64-bit versions, and a Long on 32-bit versions (4 bytes).
Function	ObjPtr	Object converter. Returns a LongPtr on 64-bit versions, and a Long on 32-bit versions (4 bytes).
Function	StrPtr	String converter. Returns a LongPtr on 64-bit versions, and a Long on 32-bit versions (4 bytes).

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.

There are two 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 Office. For code that is different between the 32-bit version and the 64-bit version, such as calling a math API that uses LongLong for its 64-bit version and Long for its 32-bit version, you use the Win64 constant. The following code shows 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 Office, you will want to use the VBA7 conditional compilation constant. However, if you write 32-bit code in Office, that code works as is in previous versions of 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.

Using conditional compilation attributes

The following example shows VBA code written for 32-bit 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.

VBA code written for 32-bit versions

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

VBA code rewritten for 64-bit versions

#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&amp;
    bInfo.ulFlags = &amp;H1
    pidList = SHBrowseForFolder(bInfo)
End Sub

Frequently asked questions

When should I use the 64-bit version of 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 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.

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 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.