std::collate
From Cppreference
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| Defined in header <locale>
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| template< class charT >
class collate |
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| This section is incomplete Reason: inheritance diagram |
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.
Two specializations are provided by the standard library and are implemented by all locale objects created in a C++ program:
| Defined in header
<locale> | |
| std::collate<chart> | implements lexicographical ordering of byte strings |
| std::collate<wchar_t> | implements lexicographical ordering of wide strings |
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[edit] Member types
| Member type | Definition |
| char_type | charT |
| string_type | std::basic_string<charT> |
[edit] Member objects
| Member name | Type |
| id (static) | std::locale::id |
[edit] Member functions
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constructs a new collate facet (public member function) |
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destructs a collate facet (protected member function) |
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Public member functions (pubic interface) | |||
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invokes do_compare (public member function) |
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invokes do_transform (public member function) |
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invokes do_hash (public member function) |
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Virtual member functions (can be overridden in a user-defined facet derived from codecvt | |||
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compares two strings using this facet's collation rules (virtual protected member function) |
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prepares a string that will collate the same as the specified string (virtual protected member function) |
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generates an integer hash value using this facet's collation rules (virtual protected member function) |
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[edit] Example
#include <locale> #include <iostream> #include <string> #include <vector> #include <algorithm> int main() { 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 förnamn zebra ängel år ögrupp English locale collation order: ängel ar år förnamn ögrupp zebra Zebra Swedish locale collation order: ar förnamn zebra Zebra år ängel ögrupp
[edit] See also
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lexicographically compares two strings using this locale's collate facet (public member function) |
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creates a collate facet for the named locale (class template) |
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