std::locale::global(std::locale("zh-CN")) Gets "Bad locale name"??

Question

Hi everyone:

       I'm playing with C/C++ locale recently.
       I've got a program which uses Chinese character as file name or in the path of a file. When using fstream to manipulate files, I choose to use MBCS instead of Unicode, so I have to specify the locale.
      At first I tried setlocale(LC_CTYPE, "chinese") and it works well, however, it's a C-style locale setting, for C++, std::locale::global() is preferable. Unfortunately, I just can't set the correct locale by calling std::locale::global(). I have tried: std::locale::global(std::locale("zh-CN")); but I get a "Bad locale name" exception, it's strange, because "zh-CN" conforms to the specification defined in MSDN(http://msdn.microsoft.com/en-us/library/dd373814(VS.85).aspx). Later I found  std::locale::global(std::locale("Chinese")); works well, then I'm totally confused. Could anybody figure it out?

Answer 1

The link you gave relates to Win32 and COM development. However, std::locale::global is a function from the C++ Standard Library. See the MSDN doucmentation for locale::global.

If I understand correctly, the strings which std::locale::global supports are implementation specific. Unfortunately, the link I provided does not show an example using Chinese. However, the example "German_germany" is given. Possibly you'll find that "Chinese_simplified" or "Chinese-simplified" is equivalent to "zh-CN".

Apache's implementation of the C++ standard library supports "zh_CN". If nothing else works for you, you could try that and see if it works in Microsoft's implementation.

This could stand to be better documented.

Answer 2

Thank you very much.
You're right, locale is platform-denpedent. I've done lots of search but find nothing about locale definition under Windows Vista Business, could anybody give me some hints.
Besides that, what should I do if I want to implement something like "setlocale(LC_CTYPE, "chinese")" by std::locale? It lacks documentation as well.

Answer 3

I had a look at the locale constructor, which takes _Locname as a parameter. Unfortunately it only gives the same example: German_germany. It does not provide a link to a list of valid _Locname values.

A few tables which don't seem to provide complete answers, but might help you guess the answer, are:

http://msdn.microsoft.com/de-de/goglobal/bb896001(en-us).aspx
http://cpansearch.perl.org/src/MARKOV/Log-Report-0.22/lib/Log/Report/Win32Locale.pm
http://docs.moodle.org/en/Table_of_locales

The tables at perl.org and moodle.org may not be directly relevant, but both contain the value "Chinese_China.936", which you could at least try. (936 is the same code page number as found in the MSDN table.)

I also found a MS Visual C++ example which uses setlocale, but has output which may reveal a useful value for the locale's constructor _Locname parameter: "Chinese_People's Republic of China.936".

I wonder if there's a MSDN forum which deals with National Language Support (NLS) questions.

Answer 4

Language and region strings are documented here .  Source code is in vc\crt\src\getqloc.c.  Culture indentifiers like zh-CN were standardized after the C++ standard library got frozen.  Standards are wonderful, so many to choose from.

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Hans Passant.

Answer 5

"Chinese_China.936" works. Thank you very much for the help!

Answer 6

you can  select "std::locale::global(std::locale(" ")); " .