Defined in header <algorithm> | ||
---|---|---|
template< class BidirIt1, class BidirIt2 > BidirIt2 copy_backward( BidirIt1 first, BidirIt1 last, BidirIt2 d_last ); |
Copies the elements from the range, defined by [first, last)
, to another range ending at d_last
. The elements are copied in reverse order (the last element is copied first), but their relative order is preserved.
The behavior is undefined if d_last
is within (first, last]
. std::copy
must be used instead of std::copy_backward
in that case.
first, last | - | the range of the elements to copy |
d_last | - | end of the destination range.. |
Type requirements | ||
-BidirIt must meet the requirements of BidirectionalIterator . |
iterator to the last element copied.
Exactly last - first
assignments.
When copying overlapping ranges, std::copy
is appropriate when copying to the left (beginning of the destination range is outside the source range) while std::copy_backward
is appropriate when copying to the right (end of the destination range is outside the source range).
template< class BidirIt1, class BidirIt2 > BidirIt2 copy_backward(BidirIt1 first, BidirIt1 last, BidirIt2 d_last) { while (first != last) { *(--d_last) = *(--last); } return d_last; } |
#include <algorithm> #include <iostream> #include <vector> int main() { std::vector<int> from_vector; for (int i = 0; i < 10; i++) { from_vector.push_back(i); } std::vector<int> to_vector(15); std::copy_backward(from_vector.begin(), from_vector.end(), to_vector.end()); std::cout << "to_vector contains: "; for (auto i: to_vector) { std::cout << i << " "; } }
Output:
to_vector contains: 0 0 0 0 0 0 1 2 3 4 5 6 7 8 9
(C++11) | copies a range of elements to a new location (function template) |
© cppreference.com
Licensed under the Creative Commons Attribution-ShareAlike Unported License v3.0.
http://en.cppreference.com/w/cpp/algorithm/copy_backward