An object of classstd::locale is an immutable indexed set of immutable facets. Each stream object of the C++ input/output library is associated with anstd::locale object and uses its facets for parsing and formatting of all data.In addition, a locale object is associated with eachstd::basic_regex object.(since C++11) Locale objects can also be used as predicates that perform string collation with the standard containers and algorithms and can be accessed directly to obtain or modify the facets they hold.

Each locale constructed in a C++ program holds at least the following standard facets (i.e.std::has_facet returnstrue for all these facet types), but a program may define additional specializations or completely new facets and add them to any existing locale object.

Internally, a locale object is implemented as if it is a reference-counted pointer to an array (indexed bystd::locale::id) of reference-counted pointers to facets: copying a locale only copies one pointer and increments several reference counts. To maintain the standard C++ library thread safety guarantees (operations on different objects are always thread-safe), both the locale reference count and each facet reference count are updated in a thread-safe manner, similar tostd::shared_ptr.

[edit]Member types

[edit]Member constants

std::locale member functions expecting acategory argument require one of the category values defined above, or the union of two or more such values. TheLC constants are not accepted.

[edit]Member functions

[edit]Example

#include <iostream>#include <locale> int main(){std::wcout<< L"User-preferred locale setting is "<< std::locale("").name().c_str()<< L'\n';// on startup, the global locale is the "C" localestd::wcout<<1000.01<< L'\n'; // replace the C++ global locale and the "C" locale with the user-preferred localestd::locale::global(std::locale(""));// use the new global locale for future wide character outputstd::wcout.imbue(std::locale()); // output the same number againstd::wcout<<1000.01<< L'\n';}

User-preferred locale setting is en_US.UTF81000.011,000.01

[edit]Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

[edit]See also

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