Language-specific operations of console applications can and should follow the locale settings of the system. This will guarantee locale-authentic formatting of numbers, date, time, currency values, and collation (sorting) operations. Locale support is available for text-mode applications through both C run-time (CRT) and Win32. Those two mechanisms can not be used interchangeably: the settings of CRT locale have no effect on Win32 code, user locale does not define the behavior of the functions exported by C run-time libraries.
For new Windows applications, Win32 mechanisms are preferred over those in CRT with regard to world-ready code.
The limitations of console system in regards to complex-script handling require special processing for locales where locale rules define complex-script output in dates or time values. However, you should avoid taking the easy route of hard-coding the format for your output. Under locales with limitations on the output text-mode applications can expose custom behavior, for example:
Always use Gregorian calendar under Hebrew User locale
Do not display AM/PM sign under Arabic User locale
Ignore digit substitution rules
CRT locale support is built around the (_w)setlocale(category, locale) call, discussed in Encodings and Code Pages part of this guide. A call to this function defines the results of all subsequent CRT-based locale-sensitive operations, not only the character encoding. The category argument defines scope of environment changes after setlocale is called.
In order to set the rules for formatting locale-sensitive data in accordance with the user locale, the following calls can be executed:
_wsetlocale (LC_COLLATE, L(".OCP") ); // sets the sort order
_wsetlocale (LC_MONETARY, L(".OCP") ); // sets the currency formatting rules
_wsetlocale (LC_NUMERIC, L(".OCP") ); // sets the formatting of numerals
_wsetlocale (LC_TIME, L(".OCP") ); // defines the date/time formatting
As mentioned in Encodings and Code Pages document, ".OCP" and ".ACP" parameters always refer to the settings of the user locale, not the system locale. While selecting this locale for LC_CTYPE or LC_ALL is not a good choice, all other categories should be set to match the user locale, unless your console must be explicitly independent of the user's settings.