23 Iterators library [iterators]

23.5 Iterator adaptors [predef.iterators]

23.5.4 Common iterators [iterators.common]

23.5.4.5 Navigation [common.iter.nav]

common_iterator& operator++();
Preconditions: holds_­alternative<I>(v_­) is true.
Effects: Equivalent to ++get<I>(v_­).
Returns: *this.
decltype(auto) operator++(int);
Preconditions: holds_­alternative<I>(v_­) is true.
Effects: If I models forward_­iterator, equivalent to: common_iterator tmp = *this; ++*this; return tmp;
Otherwise, equivalent to: return get<I>(v_­)++;