std::move_backward

 

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Defined in header <algorithm>
template<class BidirIt1, class BidirIt2 > BidirIt2 move_backward( BidirIt1 first, BidirIt1 last, BidirIt2 d_last );		(since C++11) (until C++20)
template<class BidirIt1, class BidirIt2 > constexpr BidirIt2 move_backward( BidirIt1 first, BidirIt1 last, BidirIt2 d_last );		(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.

The behavior is undefined if d_last is within (first, last]. std::move must be used instead of std::move_backward in that case.

Parameters

first, last	-	the range of the elements to move
d_last	-	end of the destination range
Type requirements
- BidirIt1, BidirIt2 must meet the requirements of BidirectionalIterator.

Return value

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

Complexity

Exactly last - first move assignments.

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;}

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).

Example

Run this code

#include <algorithm>#include <vector>#include <string>#include <iostream>   int main(){std::vector<std::string> src{"foo", "bar", "baz"};std::vector<std::string> dest(src.size());   std::cout<<"src: ";for(constauto&s : src){std::cout<< s <<' ';}std::cout<<"\ndest: ";for(constauto&s : dest){std::cout<< s <<' ';}std::cout<<'\n';   std::move_backward(src.begin(), src.end(), dest.end());   std::cout<<"src: ";for(constauto&s : src){std::cout<< s <<' ';}std::cout<<"\ndest: ";for(constauto&s : dest){std::cout<< s <<' ';}std::cout<<'\n';}

Output:

src: foo bar baz dest: src: dest: foo bar baz

See also

move (C++11)

moves a range of elements to a new location (function template)