Tag: Win32

Solving the Unicode, UTF8, UTF16 and Text Files conundrum in VBA

Understanding Unicode variants like UTF8 and UTF16 and how they impact your Office VBA development is not so straightforward. This post will guide thru the experience of reading a text file with VBA, explain some of the pitfalls you may encounter on this path when dealing with different text encodings and file formats. We’ll shed some light on essential Unicode concepts you’ve preferred to leave aside until now, because – let’s face it – who wants to spend hours reading wikipedia or MSDN just to read a text file or understand the many rules and APIs for converting between encodings ?

No bulky and verbose .NET or undecipherable C++ code complications here.
Just immediately actionable, simple and humble, VBA code with one function to rule them all, and a 10 to 15 minutes read to understand it all.

Let’s start the experience right now. Try something:

  • Open Windows notepad and copy/paste (or type) this text:

    Fancy a café ? Or a piña colada ? – Oh, that’s so cliché!

    I have a strong impression of Déjà vu.

    You hide your true motive behind a friendly façade.

    (Just my lame try to compose words with diacritics, in english. Inspiration found here and here)

  • Save the file; let’s say in c:\temp\textfiles\notepad_text.txt

Now we’ll try to read it and display it in Visual Basic, line by line, as usual:

Executing the “Test_ReadTextFileByLine” Sub (in the debug window) from this simple code snippet should do it…

…or not (!). The accented characters don’t display correctly.

Unicode, UTF8 and UTF16

Let’s state some facts before banging our heads on that:

  • Two forms of Unicode will be of interest here: UTF8 and UTF16.
  • “Windows is Unicode“, UTF16 Unicode. So is VBA. Unicode is a big character set which is meant to be able to represent the character glyphs of different languages.
  • Unicode (UTF16) encodes a character with two bytes (a “wide” character, in extension “wide” strings).
    (Note: UCS2 is history, assume UCS2 (or UCS-2) is UTF16)
  • The representation of a character in Unicode is also called a code point.
  • UTF8: not all the characters in the Unicode character set really need two bytes of encoding. UTF8 is sort of a packed representation of a series of Unicode characters, where one or two bytes can be used to represent a wide character.

Back to reading our file

At this point, we can guess that our Notepad old friend (on Windows 10 en_US version in my setup), probably stored our text file using a UTF8 encoding, which VBA is not aware of. Let’s take a look at the bytes in the file:

We see at lines 0 and 30 that our accented “é” are encoded as the two bytes C3 and A9, so this is a UTF8 file.

Then, at some point, we’ll have to convert an UTF8 representation of string to a UTF16 VBA friendly one.

Unfortunately, VBA cannot help here, so let’s take a detour to our trustworthy Win32 API.

Converting from UTF8 to UTF16 with the Win32 API

You’ll find all the code in the demo database of my reading_text_files github repository.

The function we’ll need is MultiByteToWideChar(), which we can declare as:

We’re going to have two variable sources, byte arrays and strings, to convert to UTF16, this is the VBA API functions signatures we’ll use:

Unicode normalization

There’s more than one way to represent a combination of characters in Unicode (MSDN). Extract:

Capital A with dieresis (umlaut) can be represented either as a single Unicode code point “Ä” (U+00C4) or the combination of Capital A and the combining Dieresis character (“A” + “¨”, that is, U+0041 U+0308). Similar considerations apply for many other characters with diacritic marks.

Simply put, a problem rises if we compare two Unicode strings that conceptually are the same, but use different code points (as the example above).

There are two more Win32 API functions that can help with that. One, NormalizeString(), transforms a Unicode string to a standard form, so it can be compared with another, even if the representations are different. The other, IsNormalizedString(), tests if a Unicode string is in the expected form.

There are a number of standard forms, but mainly, the one that “compresses” the code points into one character (I mean we get the attached form of “ae” instead of the “a” and “e”) is “NormalizationC”, value 1, from the following (C++) enumeration:

Normalization is an optional step, but for security considerations, should be used.
I wrapped the API (and followed MSDN guidance) in these two VBA API functions, and two others to get any error information:

Note:

I’m not following my coding guidelines for keeping error information inside a module, because we get an error either when calling Win32 API functions or a “logical” error when using the VBA API.

Then to test if something went wrong when calling UcNormalizeString() we have to test like that:

You can see a test scenario, that I sort of translated from the ones in MSDN, in the Test_Normalization() Sub, which calls:

Back to reading our file – again

Ok, now we know for sure that our file is in UTF8.
And we know that we have a nice UTF8DecodeString() at our disposal.

Are we not tempted to make this slight adaptation to our ReadTextFileByLine() function ? (see the UTF8DecodeString call in this code):

The result:

Whaaaat ? – Let’s debug that using the provided DumpStringBytes() function:

Which brings us to that output:

As we can see (and compare with the previous file’s hex dump), we do not have an UTF8 string in the variable sLine that is read by VBA from the file.

VBA converts the line it read from the file to a double byte (UTF16) string.

We cannot use VBA to read an UTF8 encoded text file using string variables.

Solution for reading and converting an UTF8 text file

We have to open the file in binary mode and read the contents in a byte array. This way VBA doesn’t do any conversion. We then just convert the byte array to an UTF8 string with the UTF8DecodeByteArrayToString().

And finally, we get it right:

Other text file encodings and BOMs

If Notepad saves files in UTF8 encoding, there are other encodings of text and file formats.

UTF8 and UTF16 text files may have, or not, a special series of bytes at the start of the file called the BOM (Byte Order Mark). The BOM is a magic number that we can use to infer the file encoding and byte endianness (order of bytes) of the file contents.

Without the BOM, guessing the file encoding can be tough.
But when there’s one, we can use it to make the necessary conversions, like in the following GetFileText() function, that can handle the following file encodings:

  • UTF16 BE / LE (Big Endian / Little Endian) with or without BOM,
  • UTF8 with or without BOM
  • ANSI (8 bits characters text, different character sets or code pages possible)

This is the signature of the function (code in the MTextFiles module of the Reading_Text_Files.accdb project), with a bit of documentation:

There’s a “text_files_samples” directory, in the github repository, with one file for each possible text file encoding.
Note that there are no UTF16 files with no BOM, as I used Notepad++ to generate the files and there’s no option in Notepad++ to generate UTF16 files with no BOM.

The Test_ReadSampleEncodings() procedure will read and check the contents of each file with this GetFileText() function:

Conclusion

We’ve seen different representation of text and encodings like UTF8, UTF16. We’re now able to convert between those encodings. And we now know how to read text from files with some of the most common file formats we may encounter, with VBA.

From here, it should be quite easy to also write any of these formats (using files open in binary mode helps).

Downloads

Head to the Reading_Text_Files github repository to get the source code, the example files and the Access demo database.

(MIT Licence)

Localization demo application screenshot

Using national language support in Office with VBA

If you need to handle multiple languages, get some specific regional settings, or do things like implement dynamic runtime language switching in your Microsoft Office solutions, you can leverage some additional help using the national language support Win32 API in VBA.

Do you know why you have to use the US English date format when you assign a date literal to a variable in VBA or in a SQL statement, surrounding it with “#” characters (like in: MyDate = #1/6/2020# for the 6 jan. 2020) ?
That’s because VBA (and the Office Object Model) is internally language locked on the locale which language ID is #1033.

What’s a locale and a language ID ? That’s how Windows manages multi language support.

There’s a lot of information about that on MSDN and on the web. Too much in fact to get started quickly.

This post will try to help you spare some time, make that journey quick and easy and jump into action now.

Here you’ll find :

  • A short review of the key concepts regarding national language support in Windows. Just what you need to know. Like what that means, and what language IDs and locales are.

  • A VBA standard module wrapping some of the most useful NLS Windows API immediately actionable.

  • A Microsoft Access database demo application using the module.
    See the short demo video:

Localization with VBA and the Win32 API demo

National language support with the Windows API

From MSDN:

The National Language Support (NLS) functions help applications support the different language- and locale-specific needs of users around the world.

The National Language Support (NLS) functions permit applications to:

  • Set the locale for the user
  • Identify the language in which the user works
  • Retrieve strings representing times, dates, and other information formatted correctly for the specified language and locale

Locales and Languages

Here’s the short version, while the full version of this topic is on MSDN.

  • In Windows, each language is identified by a 32bits Long value, the LANGUAGE ID, which has two parts:

    • The lower 16bits are the PRIMARY LANGUAGE ID
    • The higher 16bits are the SUB LANGUAGE ID

    Each language id can be translated to a string. For example, 1033 is “en_US” and 4108 is “fr_CH”. “en” is for the PRIMARY LANGUAGE ID, and “US” for the region, is the SUB LANGUAGE ID.

  • Each LANGUAGE ID has an associated LOCALE

    A “locale” is a collection of language-related user preference information represented as a list of values

  • Each value in the locale list, is indexed by (ie accessible via) a 32bits Long value, the LOCALE ID.

  • There can be multiple locales associated with one (primary) language (“en_US”, “en_GB”, etc…).

  • By using a valid LANGUAGE ID, applications can get localized strings and regional settings, like the full or abbreviated names of days and months, the region currency name and symbol, the various date and time formats, etc…

  • There is a preinstalled set of languages (and their locale settings) that ships with Windows.

    • LANG_SYSTEM_DEFAULT is a predefined constant for the language ID used to install WIndows. SUBLANG_SYS_DEFAULT represents its sub language ID.
    • LOCALE_USER_DEFAULT is a predefined constant for the language ID set for the current user.
    • There’s a predefined set of constants (LANG_*) for PRIMARY LANGUAGE IDs.
    • There’s a predefined set of constants (SUBLANG_*) for SUB LANGUAGE IDs.

Microsoft Office Application object language settings

Each VBA project in an Office application has access to a global Application object that has a:

  • LanguageSettings member that will give us a set of language IDs (MsoAppLanguageID enumeration), among which we can distinguish:

    • The language ID used to install Office (msoLanguageIDInstall),
    • The language ID in use for the current application (msoLanguageIDUI)
  • LanguagePreferredForEditing() function, that returns True, if a given language ID is used for editing (however that applies to the application).

Example (demo database)

Localization_win32.accdb, in this github repository, is an Access Database that illustrates how we can retrieve these language and regional settings from VBA.

It contains the MIntl.bas standard Visual Basic module, that wraps the necessary Win32 API functions and declarations. It also provides shortcut functions for some frequently used settings.

More on globalization

Globalization Documentation portal on MSDN.

Downloads

The files of this project are in the github repository, including the demo database (MIT license).