std::use_facet

 

C++

Language

Standard library headers

Concepts

Utilities library

Strings library

Containers library

Algorithms library

Iterators library

Numerics library

Input/output library

Localizations library

Regular expressions library (C++11)

Atomic operations library (C++11)

Thread support library (C++11)

Filesystem library (C++17)

Technical Specifications

 

Localizations library

Locales and facets
locale
use_facet	has_facet
Character classification
isspace isblank (C++11) iscntrl isupper islower isalpha	isdigit ispunct isxdigit isalnum isprint isgraph
Conversions
toupper tolower	wstring_convert (C++11) wbuffer_convert (C++11)
Facet category base classes
ctype_base codecvt_base messages_base	time_base money_base
Facet categories
ctype ctype<char> codecvt collate messages time_get time_put	num_get num_put numpunct money_get money_put moneypunct
Locale-specific facets
ctype_byname codecvt_byname messages_byname collate_byname	time_get_byname time_put_byname numpunct_byname moneypunct_byname
Code conversion facets
codecvt_utf8 (C++11) codecvt_utf16 (C++11)	codecvt_utf8_utf16 (C++11) codecvt_mode (C++11)
C locale
setlocale localeconv lconv	LC_ALLLC_COLLATELC_CTYPELC_MONETARYLC_NUMERICLC_TIME

 

Defined in header <locale>
template< class Facet > const Facet& use_facet( const std::locale& loc );

Obtains a reference to a facet implemented by loc.

Parameters

loc

-

the locale object to query

Return value

Returns a reference to the facet. The reference returned by this function is valid as long as any std::locale object exists that implements Facet.

Exceptions

std::bad_cast if std::has_facet<Facet>(loc) == false.

Example

Display the 3-letter currency name used by the user's preferred locale

Run this code

#include <iostream>
#include <locale>
 
int main()
{
    std::locale loc = std::locale(""); // user's preferred locale
    std::cout << "Your currency string is "
              << std::use_facet<std::moneypunct<char, true>>(loc).curr_symbol() << '\n';
}

Output:

Your currency string is USD

See also

locale	set of polymorphic facets that encapsulate cultural differences (class)
has_facet	checks if a locale implements a specific facet (function template)