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Showing content from https://en.cppreference.com/w/cpp/algorithm/../ranges/../algorithm/move_backward.html below:

std::move_backward - cppreference.com

template< class BidirIt1, class BidirIt2 > BidirIt2 move_backward( BidirIt1 first, BidirIt1 last, BidirIt2 d_last );

(since C++11)
(constexpr since C++20)

Moves the elements from the range [first, last), to another range ending at d_last. The elements are moved in reverse order (the last element is moved first), but their relative order is preserved.

If d_last is within (first, last], the behavior is undefined. In this case, std::move may be used instead.

[edit] Parameters first, last - the pair of iterators defining the source range of elements to move d_last - end of the destination range Type requirements -BidirIt1, BidirIt2 must meet the requirements of LegacyBidirectionalIterator. [edit] Return value

Iterator in the destination range, pointing at the last element moved.

[edit] Complexity

Exactly std::distance(first, last) move assignments.

[edit] Possible implementation

template<class BidirIt1, class BidirIt2>
BidirIt2 move_backward(BidirIt1 first, BidirIt1 last, BidirIt2 d_last)
{
    while (first != last)
        *(--d_last) = std::move(*(--last));
 
    return d_last;
}

[edit] Notes

When moving overlapping ranges, std::move is appropriate when moving to the left (beginning of the destination range is outside the source range) while std::move_backward is appropriate when moving to the right (end of the destination range is outside the source range).

[edit] Example

#include <algorithm>
#include <iostream>
#include <iterator>
#include <string>
#include <string_view>
#include <vector>
 
using container = std::vector<std::string>;
 
void print(std::string_view comment, const container& src, const container& dst = {})
{
    auto prn = [](std::string_view name, const container& cont)
    {
        std::cout << name;
        for (const auto &s : cont)
            std::cout << (s.empty() ? "â" : s.data()) << ' ';
        std::cout << '\n';
    };
    std::cout << comment << '\n';
    prn("src: ", src);
    if (dst.empty())
        return;
    prn("dst: ", dst);
}
 
int main()
{
    container src{"foo", "bar", "baz"};
    container dst{"qux", "quux", "quuz", "corge"};
    print("Non-overlapping case; before move_backward:", src, dst);
    std::move_backward(src.begin(), src.end(), dst.end());
    print("After:", src, dst);
 
    src = {"snap", "crackle", "pop", "lock", "drop"};
    print("Overlapping case; before move_backward:", src);
    std::move_backward(src.begin(), std::next(src.begin(), 3), src.end());
    print("After:", src);
}

Output:

Non-overlapping case; before move_backward:
src: foo bar baz
dst: qux quux quuz corge
After:
src: â â â
dst: qux foo bar baz
Overlapping case; before move_backward:
src: snap crackle pop lock drop
After:
src: â â snap crackle pop

[edit] See also moves a range of elements to a new location
(function template) [edit] moves a range of elements to a new location in backwards order
(algorithm function object)[edit]

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