Unicode Processing in C++

What is the best practice of Unicode processing in C++?

Solution 1:

• 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.

Solution 2:

If you don't care about backwards compatibility with previous C++ standards, the current C++11 standard has built in Unicode support: http://www.open-std.org/JTC1/SC22/WG21/docs/papers/2011/n3242.pdf

So the truly best practice for Unicode processing in C++ would be to use the built in facilities for it. That isn't always a possibility with older code bases though, with the standard being so new at present.

EDIT: To clarify, C++11 is Unicode aware in that it now has support for Unicode literals and Unicode strings. However, the standard library has only limited support for Unicode processing and conversion. For your current needs this may be enough. However, if you need to do a large amount of heavy lifting right now then you may still need to use something like ICU for more in-depth processing. There are some proposals currently in the works to include more robust support for text conversion between different encodings. My guess (and hope) is that this will be part of the next technical report.

Solution 3:

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

Solution 4:

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