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Difference between revisions of "cpp/locale/locale/locale"

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< cpp‎ | locale‎ | locale
m (Contstructs -> Constructs)
(Added LWG issue #2295 DR.)
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locale( const locale& other ) noexcept;
 
locale( const locale& other ) noexcept;
 
}}
 
}}
−
{{dcl|num=3|1=
+
{{dcl|num=3|
 
explicit locale( const char* std_name );
 
explicit locale( const char* std_name );
 
}}
 
}}
−
{{dcl|num=4|since=c++11| 1=
+
{{dcl|num=4|since=c++11|
 
explicit locale( const std::string& std_name );
 
explicit locale( const std::string& std_name );
 
}}
 
}}
−
{{dcl|num=5|1=
+
{{dcl|num=5|
−
locale( const locale& other, const char* std_name, category cat );
+
locale( const locale& other, const char* std_name, category cats );
 
}}
 
}}
−
{{dcl|num=6|since=c++11|1=
+
{{dcl|num=6|since=c++11|
−
locale( const locale& other, const std::string& std_name, category cat );
+
locale( const locale& other, const std::string& std_name, category cats );
 
}}
 
}}
−
{{dcl|num=7|1=
+
{{dcl|num=7|
 
template< class Facet >
 
template< class Facet >
 
locale( const locale& other, Facet* f );
 
locale( const locale& other, Facet* f );
 
}}
 
}}
−
{{dcl|num=8|1=
+
{{dcl|num=8|
−
locale( const locale& other, const locale& one, category cat );
+
locale( const locale& other, const locale& one, category cats );
 
}}
 
}}
 
{{dcl end}}
 
{{dcl end}}
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@3,4@ Constructs a copy of the system locale with specified {{c|std_name}} (such as {{c|"C"}}, or {{c|"POSIX"}}, or {{c|"en_US.UTF-8"}}, or {{c|"English_US.1251"}}), if such locale is supported by the operating system. The locale constructed in this manner has a name.
 
@3,4@ Constructs a copy of the system locale with specified {{c|std_name}} (such as {{c|"C"}}, or {{c|"POSIX"}}, or {{c|"en_US.UTF-8"}}, or {{c|"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 {{c|other}} except for all the facets identified by the {{c|cat}} argument, which are copied from the system locale identified by its {{c|std_name}}. The locale constructed in this manner has a name if and only if {{c|other}} has a name.
+
@4@ Equivalent to {{c|locale(std_name.c_str())}}.
  
−
@7@ Constructs a copy of {{c|other}} except for the facet of type {{tt|Facet}} (typically deduced from the type of the argument) which is installed from the argument {{c|facet}}. If {{c|facet}} is a null pointer, the constructed locale is a full copy of {{c|other}}. The locale constructed in this manner has no name. The program is ill-formed if {{tt|Facet}} is not a {{rlp|facet#Facet class|facet}} or it is a volatile-qualified facet.
+
@5@ Constructs a copy of {{c|other}} except for all the facets identified by the {{c|cats}} argument, which are copied from the system locale identified by its {{c|std_name}}. The locale constructed in this manner has a name if and only if {{c|other}} has a name.
  
−
@8@ Constructs a copy of {{c|other}} except for all the facets identified by the {{c|cat}} argument, which are copied from {{c|one}}. If both {{c|other}} and {{c|one}} have names, then the resulting locale also has a name.
+
@6@ Equivalent to {{c|locale(other, std_name.c_str(), cats)}}.
 +
 
 +
@7@ Constructs a copy of {{c|other}} except for the facet of type {{tt|Facet}} (typically deduced from the type of the argument) which is installed from {{c|f}}. If {{c|f}} is a null pointer, the constructed locale is a full copy of {{c|other}}. The program is ill-formed if {{tt|Facet}} is not a {{rlp|facet#Facet class|facet}} or it is a volatile-qualified facet.
 +
 
 +
@@ If {{c|f}} is null, the constructed locale has the same name as {{c|other}}. Otherwise, the constructed locale has no name.
 +
 
 +
@8@ Constructs a copy of {{c|other}} except for all the facets identified by the {{c|cats}} argument, which are copied from {{c|one}}.
 +
 
 +
@@ If {{c|cats}} is equal to {{tt|locale::none}}, the constructed locale has a name if and only if {{c|other}} has a name. Otherwise, the constructed locale has a name if and only if {{c|other}} and {{c|one}} both have names.
  
 
===Parameters===
 
===Parameters===
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{{par|std_name|name of the system locale to use}}
 
{{par|std_name|name of the system locale to use}}
 
{{par|f|pointer to a facet to merge with {{c|other}}}}
 
{{par|f|pointer to a facet to merge with {{c|other}}}}
−
{{par|cat|the facet category used to identify the facets to merge with {{c|other}}}}
+
{{par|cats|the facet categories used to identify the facets to merge with {{c|other}}}}
 
{{par|one|another locale to take facets from}}
 
{{par|one|another locale to take facets from}}
 
{{par end}}
 
{{par end}}
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{{dr list begin}}
 
{{dr list begin}}
 
{{dr list item|wg=lwg|dr=436|std=C++98|before=for overload {{v|7}}, it was unclear<br>whether {{tt|Facet}} can be cv-qualified|after=it can be const-qualified,<br>but not volatile-qualified}}
 
{{dr list item|wg=lwg|dr=436|std=C++98|before=for overload {{v|7}}, it was unclear<br>whether {{tt|Facet}} can be cv-qualified|after=it can be const-qualified,<br>but not volatile-qualified}}
 +
{{dr list item|wg=lwg|dr=2295|std=C++98|before=for overload {{v|7}}, the constructed locale had no name even if {{c|f}} is null|after=it has the name of {{c|other}}}}
 
{{dr list end}}
 
{{dr list end}}
  

Revision as of 00:25, 3 April 2023

 
C++
 
Localization library
 
std::locale
 
Defined in header <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.

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.
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, 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) [edit]
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