std::locale::combine

 

C++

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Feature test macros (C++20)

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Symbols index

External libraries

 

Localization library

Locales and facets
Locales
has_facet use_facet	locale
Facet category base classes
ctype_base codecvt_base messages_base	time_base money_base
ctype facets
ctype ctype<char> ctype_byname	codecvt codecvt_byname
numeric facets
num_get num_put	numpunct numpunct_byname
collate facets
collate	collate_byname
time facets
time_get time_put	time_get_byname time_put_byname
monetary facets
money_get money_put	moneypunct moneypunct_byname
messages facets
messages	messages_byname

Character classification and conversion
Character classification
isspace isblank (C++11) iscntrl	isupper islower isalpha	ispunct isdigit isxdigit	isalnum isprint isgraph

Character conversions

toupper

tolower

String and stream conversions

wstring_convert (C++11/17/26*)

wbuffer_convert (C++11/17/26*)

Text encoding identifications

text_encoding (C++26)

Unicode conversion facets

codecvt_utf8 (C++11/17/26*)

codecvt_utf16 (C++11/17/26*)

codecvt_utf8_utf16 (C++11/17/26*)

codecvt_mode (C++11/17/26*)

C library locales
LC_ALLLC_COLLATELC_CTYPELC_MONETARYLC_NUMERICLC_TIME	setlocale localeconv lconv

 

std::locale

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

 

template< class Facet > locale combine( const locale& other ) const;

Constructs a locale object which is a copy of *this except for the facet of type Facet, which is copied from other.

The program is ill-formed if Facet is not a facet or it is a volatile-qualified facet.

Return value

The new, nameless, locale.

Exceptions

std::runtime_error if other does not implement Facet.

Example

Run this code

#include <iostream>
#include <locale>
 
int main()
{
    const double number = 1000.25;
    std::cout << "\"C\" locale: " << number << '\n';
    std::locale loc = std::locale()
        .combine<std::numpunct<char>>(std::locale("en_US.UTF8"));
    std::cout.imbue(loc);
    std::cout << "\"C\" locale with en_US numpunct: " << number << '\n';
}

Output:

"C" locale: 1000.25
"C" locale with en_US numpunct: 1,000.25

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 14	C++98	locale::combine was non-const	made const
LWG 436	C++98	it was unclear whether Facet can be cv-qualified	it can be const-qualified, but not volatile-qualified

See also

(constructor)

constructs a new locale (public member function)