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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)
 
 
/*unspecified*/ operator[]( difference_type n ) const;
(since C++11)
(until C++17)
constexpr /*unspecified*/ operator[]( difference_type n ) const;
(since C++17)

Returns a reference to the element at specified relative location.

Contents

[edit] Parameters

n - position relative to current location.

[edit] Return value

An rvalue reference to the element at relative location, that is, std::move(base()[n]).

[edit] Example

#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 << 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 (size_t t{0U}; 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"

[edit] See also

(C++11)(C++11)(deprecated in C++20)
accesses the pointed-to element
(public member function) [edit]