std::reverse_iterator::base

C++

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Technical Specifications

Iterator library

Iterator primitives
iterator_traits
input_iterator_tagoutput_iterator_tagforward_iterator_tagbidirectional_iterator_tagrandom_access_iterator_tag
iterator
Iterator adaptors
reverse_iterator move_iterator (C++11) back_insert_iterator front_insert_iterator insert_iterator	make_reverse_iterator (C++14) make_move_iterator (C++11) back_inserter front_inserter inserter
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size (C++17)
empty (C++17)
data (C++17)

std::reverse_iterator

Member functions

reverse_iterator::reverse_iterator

reverse_iterator::operator=

reverse_iterator::base

reverse_iterator::operator*reverse_iterator::operator->

reverse_iterator::operator[]

reverse_iterator::operator++reverse_iterator::operator+reverse_iterator::operator+=reverse_iterator::operator--reverse_iterator::operator-reverse_iterator::operator-=

Non-member functions

operator==operator!=operator<operator>

operator+

operator-

iterator_type base() const;		(until C++17)
constexpr iterator_type base() const;		(since C++17)

Returns the underlying base iterator. That is std::reverse_iterator(it).base() == it.

The base iterator refers to the element that is next (from the std::reverse_iterator::iterator_type perspective) to the element the reverse_iterator is currently pointing to. That is &*(rit.base() - 1) == &*rit.

Parameters

(none)

Return value

The underlying iterator.

Exceptions

(none)

Example

Run this code

#include <iostream>
#include <iterator>
#include <vector>

int main()
{
  std::vector<int> v = { 0, 1, 2, 3, 4, 5 };

  using RevIt = std::reverse_iterator<std::vector<int>::iterator>;
  {
    const auto it = v.begin() + 3;
    RevIt r_it(it);

    std::cout << "*it == " << *it << ", *r_it.base() == " << *r_it.base()
    << '\n' << "*r_it == " << *r_it <<", *(r_it.base()-1) == " << *(r_it.base()-1) << "\n";
  }
  {
    RevIt r_end(v.begin());
    RevIt r_begin(v.end());

    for (auto it = r_end.base(); it != r_begin.base(); ++it) {
      std::cout << *it << " ";
    }
    std::cout << "\n";
  }
}

Output:

*it == 3, *r_it.base() == 3
*r_it == 2, *(r_it.base()-1) == 2
0 1 2 3 4 5

See also

operator*operator->

accesses the pointed-to element (public member function)