Unicode Processing in C++

• Use ICU for dealing with your data (or a similar library)
• In your own data store, make sure everything is stored in the same encoding
• Make sure you are always using your unicode library for mundane tasks like string length, capitalization status, etc. Never use standard library builtins like is_alpha unless that is the definition you want.
• I can't say it enough: never iterate over the indices of a string if you care about correctness, always use your unicode library for this.

Our company (and others) use the open source Internation Components for Unicode (ICU) library originally developed by Taligent.

It handles strings, locales, conversions, date/times, collation, transformations, et. al.

Start with the ICU Userguide

Here is a checklist for Windows programming:

• All strings enclosed in _T("my string")
• strlen() etc. functions replaced with _tcslen() etc.
• Use LPTSTR and LPCTSTR instead of char * and const char *
• When starting new projects in Dev Studio, religiously make sure the Unicode option is selected in your project properties.
• For C++ strings, use std::wstring instead of std::string

Look at Case insensitive string comparison in C++

That question has a link to the Microsoft documentation on Unicode: http://msdn.microsoft.com/en-us/library/cc194799.aspx

If you look on the left-hand navigation side on MSDN next to that article, you should find a lot of information pertaining to Unicode functions. It is part of a chapter on "Encoding Characters" (http://msdn.microsoft.com/en-us/library/cc194786.aspx)

It has the following subsections:

• The Code-Page Model
• Double-Byte Character Sets in Windows
• Unicode
• Compatibility Issues in Mixed Environments
• Unicode Data Conversion
• Migrating Windows-Based Programs to Unicode
• Summary

Although this may not be best practice for everyone, you can write your own C++ UNICODE routines if you want!

I just finished doing it over a weekend. I learned a lot, though I don't guarantee it's 100% bug free, I did a lot of testing and it seems to work correctly.

My code is under the New BSD license and can be found here:

http://code.google.com/p/netwidecc/downloads/list

It is called WSUCONV and comes with a sample main() program that converts between UTF-8, UTF-16, and Standard ASCII. If you throw away the main code, you've got a nice library for reading / writing UNICODE.

Use IBM's International Components for Unicode