std::experimental::ranges::Regular
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                    < cpp | experimental | ranges
                    
                                                            
                    | Defined in header  <experimental/ranges/concepts> | ||
| template <class T> concept bool Regular = Semiregular<T> && EqualityComparable<T>; | (ranges TS) | |
The Regular concept specifies that a type is regular, that is, it is copyable, default constructible, and equality comparable. It is satisfied by types that behave similarly to built-in types like int, and that are comparable with ==.