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    Revision as of 05:09, 14 June 2019

     
    C++
     
    Iterator library
    Iterator concepts
    Iterator primitives
    Algorithm concepts and utilities
    Indirect callable concepts
    Common algorithm requirements
    (C++20)
    (C++20)
    (C++20)
    Utilities
    (C++20)
    Iterator adaptors
    Range access
    (C++11)(C++14)
    (C++14)(C++14)  
    (C++11)(C++14)
    (C++14)(C++14)  
    (C++17)(C++20)
    (C++17)
    (C++17)
     
    std::move_iterator
     
    Defined in header <iterator> 
    template< class Iter >
class move_iterator;
    		(since C++11)

    std::move_iterator is an iterator adaptor which behaves exactly like the underlying iterator (which must be at least an LegacyInputIterator), except that dereferencing converts the value returned by the underlying iterator into an rvalue. If this iterator is used as an input iterator, the effect is that the values are moved from, rather than copied from.

    Member types

    Member type Definition
    iterator_type Iter
    difference_type std::iterator_traits<Iter>::difference_type
    pointer Iter
    value_type std::iterator_traits<Iter>::value_type
    iterator_category std::iterator_traits<Iter>::iterator_category
    reference
    value_type&& (until C++17)
    If std::iterator_traits<Iter>::reference is a reference, this is the rvalue reference version of the same type. Otherwise (such as if the wrapped iterator returns by value), this is std::iterator_traits<Iter>::reference unchanged (since C++17)

    Member functions

    		 constructs a new move_iterator
    (public member function) [edit]
    		assigns another move_iterator
    (public member function) [edit]
    		accesses the underlying iterator
    (public member function) [edit]
    		accesses the pointed-to element
    (public member function) [edit]
    		accesses an element by index
    (public member function) [edit]
    		advances or decrements the move_iterator
    (public member function) [edit]

    Member objects

    Member name Definition
    current (private) a copy of the base() iterator, the name is for exposition only

    Non-member functions

    (C++11)(C++11)(removed in C++20)(C++11)(C++11)(C++11)(C++11)(C++20)
    		 compares the underlying iterators
    (function template) [edit]
    (C++20)
    		 compares the underlying iterator and the underlying sentinel
    (function template) [edit]
    (C++11)
    		 advances the iterator
    (function template) [edit]
    (C++11)
    		 computes the distance between two iterator adaptors
    (function template) [edit]
    (C++20)
    		 computes the distance between the underlying iterator and the underlying sentinel
    (function template) [edit]
    (C++20)
    		 casts the result of dereferencing the underlying iterator to its associated rvalue reference type
    (function) [edit]
    (C++20)
    		 swaps the objects pointed to by two underlying iterators
    (function template) [edit]

    Example

    Run this code
    #include <iostream>
#include <algorithm>
#include <vector>
#include <iterator>
#include <numeric>
#include <string>

int main()
{
    std::vector<std::string> v{"this", "is", "an", "example"};

    std::cout << "Old contents of the vector: ";
    for (auto& s : v)
        std::cout << '"' << s << "\" ";

    typedef std::vector<std::string>::iterator iter_t;
    std::string concat = std::accumulate(
                             std::move_iterator<iter_t>(v.begin()),
                             std::move_iterator<iter_t>(v.end()),
                             std::string());  // Can be simplified with std::make_move_iterator

    std::cout << "\nConcatenated as string: " << concat << '\n'
              << "New contents of the vector: ";
    for (auto& s : v)
        std::cout << '"' << s << "\" ";
    std::cout << '\n';
}

    Possible output: 

    Old contents of the vector: "this" "is" "an" "example"
Concatenated as string: thisisanexample
New contents of the vector: "" "" "" ""

    See also

    (C++11)
    		 creates a std::move_iterator of type inferred from the argument
    (function template) [edit]