std::reverse_iterator<Iter>:: reverse_iterator

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C++
Iterator library
Iterator concepts
Iterator primitives
Algorithm concepts and utilities
Indirect callable concepts
Common algorithm requirements
(C++20)
(C++20)
(C++20)
Utilities
(C++20)
Iterator adaptors
Range access
(C++11) (C++14)
(C++14) (C++14)
(C++11) (C++14)
(C++14) (C++14)
(C++17) (C++20)
(C++17)
(C++17)
std::reverse_iterator
reverse_iterator ( ) ;
(1) (constexpr since C++17)
explicit reverse_iterator ( iterator_type x ) ;
(2) (constexpr since C++17)
template < class U >
reverse_iterator ( const reverse_iterator < U > & other ) ;
(3) (constexpr since C++17)

Constructs a new reverse_iterator .

Overload current
(1) value-initialized
(2) initialized with x
(3) initialized with other. current
3) The converting constructor.

This overload participates in overload resolution only if std:: is_same_v < U, Iter > is false and std:: convertible_to < const U & , Iter > is modeled.

(since C++20)

Parameters

x - iterator to adapt
other - iterator adaptor to copy

Example

Run this code 
#include <cassert>
#include <concepts>
#include <iterator>
#include <vector>
 
int main()
{
    std::vector v{0, 1, 2, 3, 4};
 
    using ReverseIt = std::reverse_iterator<std::vector<int>::const_iterator>;
 
    ReverseIt i1; // overload (1)
    i1 = v.crbegin();
    assert(*i1 == 4);
 
    ReverseIt i2(i1); // overload (2)
    assert(i2[0] == 4);
 
    int x[]{1, 2, 3};
    auto i3 = std::reverse_iterator<int*>(x + std::size(x)); // overload (1)
    i3[0] = -3;
    assert(x[2] == -3);
    std::reverse_iterator<int const*> i4(i3); // overload (3): int => const int
    static_assert(std::convertible_to<decltype(i3)::value_type,
                                      decltype(i4)::value_type>);
    // i4[0] = 5; // Error: assignment of read-only location
}

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 235 C++98 the effect of overload ( 1 ) was not specified specified
LWG 1012 C++98 overload ( 1 ) default-initialized current it is value-initialized
LWG 3435 C++20 overload ( 3 ) was not constrained constrained

See also

assigns another iterator adaptor
(public member function)
(C++14)
creates a std::reverse_iterator of type inferred from the argument
(function template)
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