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std::collate(3) 	       C++ Standard Libary		 std::collate(3)

NAME
     std::collate - std::collate

Synopsis
	Defined in header <locale>
	template< class CharT >
	class collate;

	Class  std::collate  encapsulates locale-specific collation (comparison)
     and hashing
	of strings. This facet is used by std::basic_regex and can  be	applied,
     by means of
	std::locale::operator(), directly to all standard algorithms that expect
     a string
	comparison predicate.

	std-collate-inheritance.svg

					Inheritance diagram

Specializations
	The  standard library is guaranteed to provide the following specializa-
     tions (they
	are required to be implemented by any locale object):

	Defined in header <locale>
	std::collate<char>     implements  lexicographical  ordering   of   byte
     strings
	std::collate<wchar_t>	implements   lexicographical  ordering	of  wide
     strings

Member types
	Member type Definition
	char_type   CharT
	string_type std::basic_string<CharT>

Member functions
	constructor   constructs a new collate facet
		      (public member function)
	destructor    destructs a collate facet
		      (protected member function)
	compare       invokes do_compare
		      (public member function)
	transform     invokes do_transform
		      (public member function)
	hash	      invokes do_hash
		      (public member function)

Member objects
	static std::locale::id id id of the locale
				  (public member object)

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

Example
     // Run this code

      #include <algorithm>
      #include <iostream>
      #include <locale>
      #include <string>
      #include <vector>

      int main()
      {
	  std::locale::global(std::locale("en_US.utf8"));
	  std::wcout.imbue(std::locale(""));
	  std::vector<std::wstring> v{
	      L"ar", L"zebra", L"\u00f6grupp", L"Zebra",
	      L"\u00e4ngel",L"\u00e5r", L"f\u00f6rnamn"
	  };

	  std::wcout << "Default locale collation order: ";
	  std::sort(v.begin(), v.end());
	  for (auto s : v)
	      std::wcout << s << ' ';
	  std::wcout << '\n';

	  std::wcout << "English locale collation order: ";
	  std::sort(v.begin(), v.end(), std::locale("en_US.UTF-8"));
	  for (auto s : v)
	      std::wcout << s << ' ';
	  std::wcout << '\n';

	  std::wcout << "Swedish locale collation order: ";
	  std::sort(v.begin(), v.end(), std::locale("sv_SE.UTF-8"));
	  for (auto s : v)
	      std::wcout << s << ' ';
	  std::wcout << '\n';
      }

Output:
      Default locale collation order: Zebra ar fA<paragraph>rnamn  zebra  Axngel
     AYr A<paragraph>grupp
      English	locale	 collation   order:  Axngel  ar  AYr  fA<paragraph>rnamn
     A<paragraph>grupp zebra Zebra
      Swedish locale collation order:  ar  fA<paragraph>rnamn  zebra  Zebra  AYr
     Axngel A<paragraph>grupp

See also
		       lexicographically  compares  two  strings  using this lo-
     cale's collate
	operator()     facet
		       (public member function of std::locale)
	collate_byname represents the system-supplied std::collate for the named
     locale
		       (class template)

http://cppreference.com 	   2024.06.10			 std::collate(3)
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