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

Latest revision as of 17:51, 21 October 2024

	(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.

#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

[edit] 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

[edit] See also

(destructor)

destructs the locale and the facets whose reference count becomes zero
(public member function) [edit]

[edit] External links

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

@@ Line 1: / Line 1: @@
-{{cpp/locale/locale/title | locale}}
+{{cpp/locale/locale/title|locale}}
-{{cpp/locale/locale/sidebar}}
+{{cpp/locale/locale/navbar}}
-{{ddcl list begin}}
+{{dcl begin}}
-{{ddcl list header | locale}}
+{{dcl rev multi|num=1|until1=c++11
-{{ddcl list item | num=1 | 1=
+|dcl1=
-locale();
+locale() throw();
+|dcl2=
+locale() noexcept;
 }}
-{{ddcl list item | num=2 | 1=
+{{dcl rev multi|num=2|until1=c++11
-locale( const locale& other );
+|dcl1=
+locale( const locale& other ) throw();
+|dcl2=
+locale( const locale& other ) noexcept;
 }}
-{{ddcl list item | num=3 | 1=
+{{dcl|num=3|
 explicit locale( const char* std_name );
 }}
-{{ddcl list item | num=4 | 1=
+{{dcl|num=4|since=c++11|
 explicit locale( const std::string& std_name );
 }}
-{{ddcl list item | 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 );
 }}
-{{ddcl list item | num=6 | 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 );
 }}
-{{ddcl list item | num=7 | 1=
+{{dcla|num=7|
 template< class Facet >
 locale( const locale& other, Facet* f );
 }}
-{{ddcl list item | num=8 | 1=
+{{dcl|num=8|
-locale( const locale& other, const locale& one, category cat );
+locale( const locale& other, const locale& one, category cats );
 }}
-{{ddcl list end}}
+{{dcl end}}
-) Default constructor. Constructs a copy of the global C++ locale (that is, the locale most recently used as the argument to {{cpp|std::locale::global}} or a copy of {{cpp|std::locale::classic}} if no call to {{cpp|std::locale::global}} has been made.
+Constructs a new locale object.
-) Copy constructor. Constructs a copy of {{tt|other}}.
+@1@ Default constructor. Constructs a copy of the global C++ locale, which is the locale most recently used as the argument to {{lc|std::locale::global}} or a copy of {{c|std::locale::classic()}} if no call to {{lc|std::locale::global}} has been made.
--4) Constructs a copy of the system locale with specified {{tt|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.
+@2@ Copy constructor. Constructs a copy of {{c|other}}.
--6) Constructs a copy of {{tt|other}} except for all the facets identified by the {{tt|cat}} argument, which are copied from the system locale identified by its {{tt|std_name}}. The locale constructed in this manner has the same name as {{tt|other}}.
+@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.
-) Constructs a copy of {{tt|other}} except for the facet of type {{tt|Facet}} (typically deduced from the type of the argument) which is installed from the argument {{tt|facet}}. If {{tt|facet}} is {{cpp|NULL}}, the constructed locale is a full copy of {{tt|other}}. The locale constructed in this manner has no name.
+@4@ Equivalent to {{c|locale(std_name.c_str())}}.
-) Constructs a copy of {{tt|other}} except for all the facets identified by the {{tt|cat}} argument, which are copied from {{tt|one}}. If both {{tt|other}} and {{tt|one}} have names, then the resulting locale also has a name.
+@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.
-===Parameters===
+@6@ Equivalent to {{c|locale(other, std_name.c_str(), cats)}}.
-{{param list begin}}
-{{param list item | other | another locale to copy}}
-{{param list item | std_name | name of the system locale to use}}
-{{param list item | f | pointer to a facet to merge with {{tt|other}} }}
-{{param list item | cat | the locale category used to identify the facets to merge with {{tt|other}} }}
-{{param list item | one | another locale to take facets from}}
-{{param list end}}
-===Exceptions===
+@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.
--2) {{noexcept}}
-) {{cpp|std::runtime_error}} if the operating system has no locale named {{tt|std_name}} or if {{tt|std_name}} is {{cpp|NULL}}.
+@@ If {{c|f}} is null, the constructed locale has the same name as {{c|other}}. Otherwise, the constructed locale has no name.
-) {{cpp|std::runtime_error}} if the operating system has no locale named {{tt|std_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}}.
-) {{cpp|std::runtime_error}} if the operating system has no locale named {{tt|std_name}} or if {{tt|std_name}} is {{cpp|NULL}}.
+@@ 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.
-) {{cpp|std::runtime_error}} if the operating system has no locale named {{tt|std_name}}.
+===Parameters===
+{{par begin}}
+{{par|other|another locale to copy}}
+{{par|std_name|name of the system locale to use}}
+{{par|f|pointer to a facet 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 end}}
--8) (none)
+===Exceptions===
+@3,5@ {{lc|std::runtime_error}} if the operating system has no locale named {{c|std_name}} or if {{c|std_name}} is a null pointer.
+@4,6@ {{lc|std::runtime_error}} if the operating system has no locale named {{c|std_name}}.
+===Notes===
+Overload {{vl|7}} is typically called with its second argument, {{c|f}}, obtained directly from a new-expression: the locale is responsible for calling the matching {{c/core|delete}} from its own destructor.
 ===Example===
-{{example cpp
+{{example
- |
+|code=
- | code=
+#include <codecvt>
 #include <iostream>
 #include <locale>
-#include <codecvt>
+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;  // l1 is a copy of the classic "C" locale
+     std::locale l1;
-     std::locale l2("en_US.UTF-8"); // l2 is a unicode locale
+    std::cout << "Name of a copy of the classic \"C\" locale: " << l1;
-     std::locale l3(l1, l2, std::locale::ctype); // l3 is "C" except for ctype, which is unicode
-     std::locale l4(l1, new std::codecvt_utf8<wchar_t>); // l4 is "C" except for codecvt
+     std::locale l2("en_US.UTF-8");
-     std::cout << "Locale names:\nl1: " << l1.name() << "\nl2: " << l2.name()
+     std::cout << "Name of unicode locale: " << l2;
-               << "\nl3: " << l3.name() << "\nl4: " << l4.name() << '\n';
+     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;
 }
- | output=
+|p=true
-Locale names:
+|output=
-l1: C
+Name of a copy of the classic "C" locale: C
-l2: en_US.UTF-8
+Name of unicode locale: 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
+Name of "C" locale except for codecvt: *
-l4: *
+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===
+{{dr list begin}}
+{{dr list item|wg=lwg|dr=436|std=C++98|before=for overload {{vl|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 {{vl|7}}, the constructed locale had no name even if {{c|f}} is null|after=it has the name of {{c|other}}}}
+{{dr list end}}
 ===See also===
-{{dcl list begin}}
+{{dsc begin}}
-{{dcl list template | cpp/locale/locale/dcl list ~locale}}
+{{dsc inc|cpp/locale/locale/dsc ~locale}}
-{{dcl list end}}
+{{dsc end}}
+===External links===
+{{elink begin}}
+{{elink|num=1|1=[https://ss64.com/locale.html List of Windows locale names].}}
+{{elink|num=2|1=[https://lh.2xlibre.net/locales/ List of Linux locale names].}}
+{{elink end}}
+{{langlinks|de|es|fr|it|ja|pt|ru|zh}}

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Character conversions
toupper
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Member types
locale::id
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Member functions
locale::locale
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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

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

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

Latest revision as of 17:51, 21 October 2024

Contents

[edit] Parameters

[edit] Exceptions

[edit] Notes

[edit] Example

[edit] Defect reports

[edit] See also

[edit] External links

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