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

From cppreference.com
 
 
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)
reference operator* () const;
(until C++17)
constexpr reference operator* () const;
(since C++17)
(2)
pointer operator->() const;
(until C++17)
constexpr pointer operator->() const;
(since C++17)
(deprecated in C++20)

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

1) Equivalent to static_cast<reference>(*base()).
2) Equivalent to base().

Contents

[edit] Parameters

(none)

[edit] 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.

[edit] 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.

[edit] Example

#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 << 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 );
    }
    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
}

Output:

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

[edit] 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 2106 C++11 dereferencing a move_iterator could return a dangling reference
if the dereferencing the underlying iterator returns a prvalue
returns the object instead

[edit] See also

accesses an element by index
(public member function) [edit]