# iter_move(std::common_iterator)

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< cpp‎ | iterator‎ | common iterator

friend constexpr decltype(auto) iter_move( const std::common_iterator & i ) noexcept(noexcept( ranges::iter_move ( std::declval <const I&>())) requires std::input_iterator <I>; |  | (since C++20)

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

The function body is equivalent to: return std:: ranges::iter_move (std::get<I>(i.var));.

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

If i.var does not hold an `I` object (i.e. an iterator), the behavior is undefined.

### Parameters

i | - | a source iterator adaptor

### Return value

An rvalue reference or a prvalue temporary.

### Complexity

Constant.

### Example

Run this code

    #include <iomanip>
    #include <iostream>
    #include <iterator>
    #include <string>
    #include <vector>

    void print(auto const& rem, auto const& v)
    {
        std::cout << rem << '[' << size(v) << "] { ";
        for (int o{}; auto const& s : v)
            std::cout << (o++ ? ", " : "") << std::quoted(s);
        std::cout << " }\n";
    }

    int main()
    {
        std::vector<std::string> p{"Andromeda", "Cassiopeia", "Phoenix"}, q;
        print("p", p);
        print("q", q);

        using CTI = std::counted_iterator<std::vector<std::string>::iterator>;
        using CI = std::common_iterator<CTI, std::default_sentinel_t>;
        CI last{std::default_sentinel};

        for (CI first{{p.begin(), 2}}; first != last; ++first)
            q.emplace_back(/* ADL */ iter_move(first));

        print("p", p);
        print("q", q);
    }

Possible output:

    p[3] { "Andromeda", "Cassiopeia", "Phoenix" }
    q[0] {  }
    p[3] { "", "", "Phoenix" }
    q[2] { "Andromeda", "Cassiopeia" }

### 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 3953 | C++20 | the return type was std::iter_rvalue_reference_t <I> | changed to decltype(auto)

### See also

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) | converts the argument to an xvalue (function template)
move_if_noexcept (C++11) | converts the argument to an xvalue if the move constructor does not throw (function template)
forward (C++11) | forwards a function argument and use the type template argument to preserve its value category (function template)
ranges::move (C++20) | moves a range of elements to a new location (algorithm function object)
ranges::move_backward (C++20) | moves a range of elements to a new location in backwards order (algorithm function object)

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