std::locale::locale
From cppreference.com
Defined in header <locale>
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(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 cat ); |
(5) | |
locale( const locale& other, const std::string& std_name, category cat ); |
(6) | (since C++11) |
template< class Facet > locale( const locale& other, Facet* f ); |
(7) | |
locale( const locale& other, const locale& one, category cat ); |
(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.
5,6) Constructs a copy of other except for all the facets identified by the cat 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.
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 the argument facet. If facet is a null pointer, the constructed locale is a full copy of other. The locale constructed in this manner has no name. The program is ill-formed if Facet
is not a facet or it is a volatile-qualified facet.8) Constructs a copy of other except for all the facets identified by the cat argument, which are copied from one. If both other and one have names, then the resulting locale also has a name.
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 |
cat | - | the facet category 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 |
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LWG 436 | C++98 | for overload (7), it was unclear whether Facet can be cv-qualified
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it can be const-qualified, but not volatile-qualified |
See also
destructs the locale and the facets whose reference count becomes zero (public member function) |