std::move_iterator<Iter>::base

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Iterator library
Iterator concepts
Iterator primitives
Algorithm concepts and utilities
Indirect callable concepts
Common algorithm requirements
Utilities
(C++20)
Iterator adaptors
Stream iterators
Iterator customization points
Iterator operations
(C++11)
(C++11)
Range access
(C++11)(C++14)
(C++11)(C++14)
(C++17)(C++20)
(C++14)(C++14)
(C++14)(C++14)
(C++17)
(C++17)
 
 
(1)
iterator_type base() const;
(since C++11)
(until C++17)
constexpr iterator_type base() const;
(since C++17)
(until C++20)
constexpr const iterator_type& base() const& noexcept;
(since C++20)
constexpr iterator_type base() &&;
(2) (since C++20)

Returns the underlying base iterator.

1) Copy constructs the return value from the underlying iterator.
(until C++20)
1) Returns a reference to the underlying iterator.
(since C++20)
2) Move constructs the return value from the underlying iterator.

Parameters

(none)

Return value

1) A copy of the underlying iterator.
(until C++20)
1) A reference to the underlying iterator.
(since C++20)
2) An iterator move constructed from the underlying iterator.

Exceptions

May throw implementation-defined exceptions.

Example

#include <algorithm>
#include <iostream>
#include <iterator>
#include <vector>
 
int main()
{
    std::vector<int> v{ 0, 1, 2, 3, 4 };
    std::move_iterator<std::vector<int>::reverse_iterator>
        m1{ v.rbegin() },
        m2{ v.rend() };
 
    std::copy(m1.base(), m2.base(), std::ostream_iterator<int>(std::cout, " "));
    std::cout << '\n';
}

Output:

4 3 2 1 0

Defect reports

The following behavior-changing defect reports were applied retroactively to previously published C++ standards.

DR Applied to Behavior as published Correct behavior
LWG 3391 C++20 the const version of base returns a copy of the underlying iterator returns a reference
LWG 3593 C++20 the const version of base returns a reference but might not be noexcept made noexcept

See also

(C++11)(C++11)(deprecated in C++20)
accesses the pointed-to element
(public member function)