How to get current locale of my environment?

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.