How to get current locale of my environment? - c++

Question

Had tried following code in Linux, but always return 'C' under different LANG settings.
#include <iostream>
#include <locale.h>
#include <locale>
using namespace std;
int main()
{
cout<<"locale 1: "<<setlocale(LC_ALL, NULL)<<endl;
cout<<"locale 2: "<<setlocale(LC_CTYPE, NULL)<<endl;
locale l;
cout<<"locale 3: "<<l.name()<<endl;
}
$ ./a.out
locale 1: C
locale 2: C
locale 3: C
$
$ export LANG=zh_CN.UTF-8
$ ./a.out
locale 1: C
locale 2: C
locale 3: C
What should I do to get current locale setting in Linux(like Ubuntu)?
Another question is, is it the same way to get locale in Windows?

Answer 1

From man 3 setlocale (New maxim: "When in doubt, read the entire manpage."):
If locale is "", each part of the locale that should be modified is set according to the environment variables.
So, we can read the environment variables by calling setlocale at the beginning of the program, as follows:
#include <iostream>
#include <locale.h>
using namespace std;
int main()
{
setlocale(LC_ALL, "");
cout << "LC_ALL: " << setlocale(LC_ALL, NULL) << endl;
cout << "LC_CTYPE: " << setlocale(LC_CTYPE, NULL) << endl;
return 0;
}
My system does not support the zh_CN locale, as the following output reveals:
$ ./a.out
LC_ALL: en_US.utf8
LC_CTYPE: en_US.utf8
$ export LANG=zh_CN.UTF-8
$ ./a.out
LC_ALL: C
LC_CTYPE: C
Windows: I have no idea about Windows locales. I suggest starting with an MSDN search, and then opening a separate Stack Overflow question if you still have questions.

Answer 2

Just figured out how to get locale by C++, simply use an empty string "" to construct std::locale, which does the same thing as setlocale(LC_ALL, "").
locale l("");
cout<<"Locale by C++: "<<l.name()<<endl;
This link described differences in details between C locale and C++ locale.

Answer 3

For Windows use the following code:
LCID lcid = GetThreadLocale();
wchar_t name[LOCALE_NAME_MAX_LENGTH];
if (LCIDToLocaleName(lcid, name, LOCALE_NAME_MAX_LENGTH, 0) == 0)
error(GetLastError());
std::wcout << L"Locale name = " << name << std::endl;
This is going to print something like "en-US".
To purge sublanguage information use the following:
wchar_t parentLocateName[LOCALE_NAME_MAX_LENGTH];
if (GetLocaleInfoEx(name, LOCALE_SPARENT, parentLocateName, LOCALE_NAME_MAX_LENGTH) == 0)
error(GetLastError());
std::wcout << L"parentLocateName = " << parentLocateName << std::endl;
This will give you just "en".

Answer 4

A good alternative to consider instead of std::locale is boost::locale which is capable of returning more reliable information - see http://www.boost.org/doc/libs/1_52_0/libs/locale/doc/html/locale_information.html
boost::locale::info has the following member functions:
std::string name() -- the full name of the locale, for example en_US.UTF-8
std::string language() -- the ISO-639 language code of the current locale, for example "en".
std::string country() -- the ISO-3199 country code of the current locale, for example "US".
std::string variant() -- the variant of current locale, for example "euro".
std::string encoding() -- the encoding used for char based strings, for example "UTF-8"
bool utf8() -- a fast way to check whether the encoding is UTF-8.

Answer 5

The default constructor of std::locale creates a copy of the global C++ locale.
So to get the name of the current locale:
std::cout << std::locale().name() << '\n';