std::collate - cppreference.com (original) (raw)

| | | | | --------------------------------------- | | | | 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.

Inheritance diagram

[edit] Specializations

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


std::collate<char>	implements lexicographical ordering of byte strings
std::collate<wchar_t>	implements lexicographical ordering of wide strings

[edit] Nested types

[edit] Data members

[edit] Member functions

[edit] Protected member functions

| | compares two strings using this facet's collation rules (virtual protected member function) [edit] | | ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | | transforms a string so that collation can be replaced by comparison (virtual protected member function) [edit] | | | generates an integer hash value using this facet's collation rules (virtual protected member function) [edit] |

[edit] Example

#include #include #include #include #include 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 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

| | lexicographically compares two strings using this locale's collate facet (public member function of std::locale) [edit] | | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | | represents the system-supplied std::collate for the named locale (class template) [edit] |