NAME¶

std::move_iterator::operator*,-> - std::move_iterator::operator*,->

Synopsis¶

reference operator* () const; (1) (since C++11)
(constexpr since C++17)
(since C++11)
pointer operator->() const; (2) (constexpr since C++17)
(deprecated in C++20)

Returns an rvalue-reference or pointer to the current element.

1) Equivalent to
static_cast<reference>(*base())
(until C++20)
ranges::iter_move(base())
(since C++20).
2) Equivalent to base().

Parameters¶

(none)

Return value¶

1) Rvalue-reference to the current element or its copy.
2) Copy of the underlying iterator. A pointer to the current element is eventually
returned if -> is directly used.

Notes¶

Note that (2) eventually returns a pointer if -> is directly used. When
dereferencing a pointer the returned value is an lvalue. This may lead to unintended
behavior.

Example¶

// Run this code

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

void print(auto rem, auto const& v)
{
for (std::cout << rem; auto const& e : v)
std::cout << std::quoted(e) << ' ';
std::cout << '\n';
}

int main()
{
std::vector<std::string> p{"alpha", "beta", "gamma", "delta"}, q;
print("1) p: ", p);
for (std::move_iterator it{p.begin()}, end{p.end()}; it != end; ++it)
{
it->push_back('!'); // calls -> string::push_back(char)
q.emplace_back(*it); // *it <- overload (1)
}
print("2) p: ", p);
print("3) q: ", q);

std::vector v{1, 2, 3};
std::move_iterator it{v.begin()};
// *it = 13; // error: using rvalue as lvalue
}

Possible output:¶

1) p: "alpha" "beta" "gamma" "delta"
2) p: "" "" "" ""
3) q: "alpha!" "beta!" "gamma!" "delta!"

Defect reports

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

DR Applied to Behavior as published Correct behavior
dereferencing a move_iterator could return a
LWG 2106 C++11 dangling reference returns the object
if the dereferencing the underlying iterator instead
returns a prvalue

See also¶

operator[] accesses an element by index
(C++11) (public member function)