24 Ranges library [ranges]

24.7 Range adaptors [range.adaptors]

24.7.15 Reverse view [range.reverse]

24.7.15.1 Overview [range.reverse.overview]

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reverse_­view takes a bidirectional view and produces another view that iterates the same elements in reverse order.
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The name views​::​reverse denotes a range adaptor object ([range.adaptor.object]).
Given a subexpression E, the expression views​::​reverse(E) is expression-equivalent to:
  • (2.1)
    If the type of E is a (possibly cv-qualified) specialization of reverse_­view, equivalent to E.base().
  • (2.2)
    Otherwise, if the type of E is cv subrange<reverse_­iterator<I>, reverse_­iterator<I>, K> for some iterator type I and value K of type subrange_­kind,
    • (2.2.1)
      if K is subrange_­kind​::​sized, equivalent to: subrange<I, I, K>(E.end().base(), E.begin().base(), E.size())
    • (2.2.2)
      otherwise, equivalent to: subrange<I, I, K>(E.end().base(), E.begin().base())
    However, in either case E is evaluated only once.
  • (2.3)
    Otherwise, equivalent to reverse_­view{E}.
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[Example 1: vector<int> is {0,1,2,3,4}; reverse_view rv {is}; for (int i : rv) cout << i << ' '; // prints: 4 3 2 1 0 — end example]