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std::iter_move(std::reverse_iterator)

friend constexpr std::iter_rvalue_reference_t<Iter>
    iter_move( const std::reverse_iterator& i ) noexcept(/* see below */);

(since C++20)

Casts the result of dereferencing the adjusted underlying iterator to its associated rvalue reference type.

The function body is equivalent to:

auto tmp = i.base();
return std::ranges::iter_move(--tmp);

This function template is not visible to ordinary unqualified or qualified lookup, and can only be found by argument-dependent lookup when std::reverse_iterator<Iter> is an associated class of the arguments.

Parameters

a source reverse iterator.

Return value

An rvalue reference or a prvalue temporary.

Complexity

Constant.

Exceptions

noexcept specification:

noexcept(
 std::is_nothrow_copy_constructible_v<Iter> &&
 noexcept(std::ranges::iter_move(--std::declval<Iter&>()))
.
)

Example

#include <iomanip>
#include <iostream>
#include <iterator>
#include <string>
#include <vector>
 
void print(auto const& rem, auto const& v) {
    for (std::cout << rem << "[" << size(v) << "] { "; auto const& s : v)
        std::cout << quoted(s) << " ";
    std::cout << "}\n";
}
 
int main()
{
    std::vector<std::string> p { "Alpha", "Bravo", "Charlie" }, q;
 
    print("p", p), print("q", q);
 
    using RI = std::reverse_iterator<std::vector<std::string>::iterator>;
 
    for (RI iter{ p.rbegin() }, rend{ p.rend() }; iter != rend; ++iter) {
        q.emplace_back( /* ADL */ iter_move(iter) );
    }
 
    print("p", p), print("q", q);
}

Possible output:

p[3] { "Alpha" "Bravo" "Charlie" }
q[0] { }
p[3] { "" "" "" }
q[3] { "Charlie" "Bravo" "Alpha" }

iter_move (C++20)	casts the result of dereferencing an object to its associated rvalue reference type (customization point object)
iter_move (C++20)	casts the result of dereferencing the underlying iterator to its associated rvalue reference type (function)
move (C++11)	obtains an rvalue reference (function template)
move_if_noexcept (C++11)	obtains an rvalue reference if the move constructor does not throw (function template)
forward (C++11)	forwards a function argument (function template)
ranges::move (C++20)	moves a range of elements to a new location (niebloid)
ranges::move_backward (C++20)	moves a range of elements to a new location in backwards order (niebloid)