std::move_iterator::operator[](3)

NAME
std::move_iterator::operator[] - std::move_iterator::operator[]

Synopsis
   /* unspecified */ operator[]( difference_type n ) const; (since C++11)
                        (until C++17)
   constexpr /* unspecified */ operator[]( difference_type n ) const; (since C++17)
                        (until C++20)
   constexpr reference operator[]( difference_type n ) const; (since C++20)
   Returns a reference to the element at specified relative location.

Parameters
   n - position relative to current location

Return value
   An rvalue reference to the element at relative location, that is,
   std::move(base()[n])
   (until C++20)
   ranges::iter_move(base() + n)
   (since C++20).

Notes
   The return type is unspecified because the return type of the
   underlying iterator's operator[] is also unspecified (see (until C++20)
   LegacyRandomAccessIterator).

Example
// Run this code
 #include <cstddef>
 #include <iomanip>
 #include <iostream>
 #include <iterator>
 #include <list>
 #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);
     std::move_iterator it{p.begin()};
     for (std::size_t t{}; t != p.size(); ++t)
         q.emplace_back(it[t]);
     print("2) p: ", p);
     print("3) q: ", q);
     std::list l{1, 2, 3};
     std::move_iterator it2{l.begin()};
 // it2[1] = 13; // compilation error: the underlying iterator
                  // does not model the random access iterator
 // *it2 = 999; // compilation error: using rvalue as lvalue
 }

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

See also
   operator*
   operator-> accesses the pointed-to element
   (C++11) (public member function)
   (C++11)(deprecated in C++20)