std::collate_byname

C++

Language

Headers

Freestanding and hosted implementations

Named requirements

Language support library

Concepts library (C++20)

Diagnostics library

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 CharT > class collate_byname : public std::collate<CharT>;

std::collate_byname is a std::collate facet which encapsulates locale-specific collation (comparison) and hashing of strings. Just like std::collate, it can be imbued in std::regex and applied, by means of std::locale::operator(), directly to all standard algorithms that expect a string comparison predicate.

Two specializations are provided by the standard library

Defined in header <locale>
std::collate_byname<char>	locale-specific collation of multibyte strings
std::collate_byname<wchar_t>	locale-specific collation of wide strings

Member functions

(constructor)	constructs a new collate_byname facet (public member function)
(destructor)	destroys a collate_byname facet (protected member function)

std::collate_byname::collate_byname

explicit collate_byname( const char* name, std::size_t refs = 0 );
explicit collate_byname( const std::string& name, std::size_t refs = 0 );		(since C++11)

Constructs a new std::collate_byname facet for a locale with name.

refs is used for resource management: if refs == 0, the implementation destroys the facet, when the last std::locale object holding it is destroyed. Otherwise, the object is not destroyed.

Parameters

name	-	the name of the locale
refs	-	the number of references that link to the facet

std::collate_byname::~collate_byname

protected: ~collate_byname();

Destroys the facet.

Inherited from std::collate

Member types

Member type	Definition
char_type	charT
string_type	std::basic_string<charT>

Member functions

compare	invokes do_compare (public member function of std::collate)
transform	invokes do_transform (public member function of std::collate)
hash	invokes do_hash (public member function of std::collate)

Protected member functions

do_compare [virtual]	compares two strings using this facet's collation rules (virtual protected member function of std::collate)
do_transform [virtual]	transforms a string so that collation can be replaced by comparison (virtual protected member function of std::collate)
do_hash [virtual]	generates an integer hash value using this facet's collation rules (virtual protected member function of std::collate)

Notes

Collation order is the dictionary order: the position of the letter in the national alphabet (its equivalence class) has higher priority than its case or variant. Within an equivalence class, lowercase characters collate before their uppercase equivalents and locale-specific order may apply to the characters with diacritics. In some locales, groups of characters compare as single collation units. For example, "ch" in Czech follows "h" and precedes "i", and "dzs" in Hungarian follows "dz" and precedes "g".

See also

collate	defines lexicographical comparison and hashing of strings (class template)
strcoll	compares two strings in accordance to the current locale (function)
wcscoll	compares two wide strings in accordance to the current locale (function)
operator()	lexicographically compares two strings using this locale's collate facet (public member function of std::locale)