std::locale::locale

	(1)
locale() throw();			(until C++11)
locale() noexcept;			(since C++11)
		(2)
locale( const locale& other ) throw();				(until C++11)
locale( const locale& other ) noexcept;				(since C++11)
explicit locale( const char* std_name );			(3)
explicit locale( const std::string& std_name );			(4)	(since C++11)
locale( const locale& other, const char* std_name, category cats );			(5)
locale( const locale& other, const std::string& std_name, category cats );			(6)	(since C++11)
template< class Facet > locale( const locale& other, Facet* f );			(7)
locale( const locale& other, const locale& one, category cats );			(8)

Constructs a new locale object.

1) Default constructor. Constructs a copy of the global C++ locale, which is the locale most recently used as the argument to std::locale::global or a copy of std::locale::classic() if no call to std::locale::global has been made.

2) Copy constructor. Constructs a copy of other.

3,4) Constructs a copy of the system locale with specified std_name (such as "C", or "POSIX", or "en_US.UTF-8", or "English_US.1251"), if such locale is supported by the operating system. The locale constructed in this manner has a name.

4) Equivalent to locale(std_name.c_str()).

5) Constructs a copy of other except for all the facets identified by the cats argument, which are copied from the system locale identified by its std_name. The locale constructed in this manner has a name if and only if other has a name.

6) Equivalent to locale(other, std_name.c_str(), cats).

7) Constructs a copy of other except for the facet of type Facet (typically deduced from the type of the argument) which is installed from f. If f is a null pointer, the constructed locale is a full copy of other. The program is ill-formed if Facet is not a facet or it is a volatile-qualified facet.

If f is null, the constructed locale has the same name as other. Otherwise, the constructed locale has no name.

8) Constructs a copy of other except for all the facets identified by the cats argument, which are copied from one.

If cats is equal to locale::none, the constructed locale has a name if and only if other has a name. Otherwise, the constructed locale has a name if and only if other and one both have names.

Parameters

other	-	another locale to copy
std_name	-	name of the system locale to use
f	-	pointer to a facet to merge with other
cats	-	the facet categories used to identify the facets to merge with other
one	-	another locale to take facets from

Exceptions

3,5) std::runtime_error if the operating system has no locale named std_name or if std_name is a null pointer.

4,6) std::runtime_error if the operating system has no locale named std_name.

Notes

Overload (7) is typically called with its second argument, f, obtained directly from a new-expression: the locale is responsible for calling the matching delete from its own destructor.

Example

Run this code

#include <codecvt>
#include <iostream>
#include <locale>
 
std::ostream& operator<< (std::ostream& os, const std::locale& loc)
{
    if (loc.name().length() <= 80)
        os << loc.name();
    else
        for (const auto c : loc.name())
            os << c << (c == ';' ? "\n  " : "");
 
    return os << '\n';
}
 
int main()
{
    std::locale l1;
    std::cout << "Name of a copy of the classic \"C\" locale: " << l1;
 
    std::locale l2("en_US.UTF-8");
    std::cout << "Name of unicode locale: " << l2;
 
    std::locale l3(l1, new std::codecvt_utf8<wchar_t>);
    std::cout << "Name of \"C\" locale except for codecvt: " << l3;
 
    std::locale l4(l1, l2, std::locale::ctype);
    std::cout << "Name of \"C\" locale except for ctype, which is unicode:\n  " << l4;
}

Possible output:

Name of a copy of the classic "C" locale: C
Name of unicode locale: en_US.UTF-8
Name of "C" locale except for codecvt: *
Name of "C" locale except for ctype, which is unicode:
  LC_CTYPE=en_US.UTF-8;
  LC_NUMERIC=C;
  LC_TIME=C;
  LC_COLLATE=C;
  LC_MONETARY=C;
  LC_MESSAGES=C;
  LC_PAPER=C;
  LC_NAME=C;
  LC_ADDRESS=C;
  LC_TELEPHONE=C;
  LC_MEASUREMENT=C;
  LC_IDENTIFICATION=C

Defect reports

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

DR	Applied to	Behavior as published	Correct behavior
LWG 436	C++98	for overload (7), it was unclear whether `Facet` can be cv-qualified	it can be const-qualified, but not volatile-qualified
LWG 2295	C++98	for overload (7), the constructed locale had no name even if f is null	it has the name of other

External links

1.	List of Windows locale names.
2.	List of Linux locale names.

Compiler support
Freestanding and hosted
Language
Standard library
Standard library headers
Named requirements
Feature test macros (C++20)
Language support library
Concepts library (C++20)
Metaprogramming library (C++11)
Diagnostics library
General utilities library
Strings library
Containers library
Iterators library
Ranges library (C++20)
Algorithms library
Numerics library
Localizations library
Input/output library
Filesystem library (C++17)
Regular expressions library (C++11)
Concurrency support library (C++11)
Execution support library (C++26)
Technical specifications
Symbols index
External libraries

Character conversions
toupper
tolower
String and stream conversions
wstring_convert (C++11/17/26*)
wbuffer_convert (C++11/17/26*)

Member types
locale::id
locale::facet
Member functions
locale::locale
locale::~locale
locale::operator=
locale::combine
locale::name
locale::encoding (C++26)
locale::operator==locale::operator!= (until C++20)
locale::operator()
Static member functions
locale::global
locale::classic