std::locale::locale
From cppreference.com
| (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.Contents |
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.
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, std::locale const& loc) { if (loc.name().length() <= 80) return os << loc.name() << '\n'; for (const auto c : loc.name()) c != ';' ? os << c : os << "\n "; return os << '\n'; } int main() { // l1 is a copy of the classic "C" locale std::locale l1; // l2 is a unicode locale std::locale l2("en_US.UTF-8"); // l3 is "C" except for ctype, which is unicode std::locale l3(l1, l2, std::locale::ctype); // l4 is "C" except for codecvt std::locale l4(l1, new std::codecvt_utf8<wchar_t>); std::cout << "Locale names:\n" << "l1: " << l1 << "l2: " << l2 << "l3: " << l3 << "l4: " << l4; }
Possible output:
Locale names:
l1: C
l2: en_US.UTF-8
l3: 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
l4: *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 |
See also
| destructs the locale and the facets whose reference count becomes zero (public member function) |
External links
| 1. | List of Windows locale names. |
| 2. | List of Linux locale names. |
