28 Localization library [localization]

28.4 Standard locale categories [locale.categories]

28.4.5 The collate category [category.collate]

28.4.5.1 Class template collate [locale.collate]

28.4.5.1.1 General [locale.collate.general]

namespace std { template<class charT> class collate : public locale::facet { public: using char_type = charT; using string_type = basic_string<charT>; explicit collate(size_t refs = 0); int compare(const charT* low1, const charT* high1, const charT* low2, const charT* high2) const; string_type transform(const charT* low, const charT* high) const; long hash(const charT* low, const charT* high) const; static locale::id id; protected: ~collate(); virtual int do_compare(const charT* low1, const charT* high1, const charT* low2, const charT* high2) const; virtual string_type do_transform(const charT* low, const charT* high) const; virtual long do_hash (const charT* low, const charT* high) const; }; }
The class collate<charT> provides features for use in the collation (comparison) and hashing of strings.
A locale member function template, operator(), uses the collate facet to allow a locale to act directly as the predicate argument for standard algorithms ([algorithms]) and containers operating on strings.
The specializations required in Table 104 ([locale.category]), namely collate<char> and collate<wchar_­t>, apply lexicographic ordering ([alg.lex.comparison]).
Each function compares a string of characters *p in the range [low, high).