C++ Algorithm Library - copy_backward() Function

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Description

The C++ function std::algorithm::copy_backward() copies a range of elements to a new location in backward order.

Declaration

Following is the declaration for std::algorithm::copy_backward() function form std::algorithm header.

C++98

template <class BidirectionalIterator1, class BidirectionalIterator2>
BidirectionalIterator2 copy_backward(BidirectionalIterator1 first,
   BidirectionalIterator1 last, BidirectionalIterator2 result);

Parameters

• first − Bidirectional iterators to the initial positions in a sequence.

• last − Bidirectional iterators to the final positions in a sequence.

• result − Bidirectional iterator to the past-the-end position in the destination sequence.

Return value

Returns an iterator to the first element of the destination sequence where elements have been copied.

Exceptions

Throws an exception if either element assignment or an operation on an iterator throws exception.

Please note that invalid parameters cause undefined behavior.

Time complexity

Linear in the distance between first to last.

Example

The following example shows the usage of std::algorithm::copy_backward() function.

#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

int main(void) {
   vector<int> v1 = {1, 2, 3, 4, 5};
   vector<int> v2(5);

   copy_backward(v1.begin(), v1.end(), v2.end());

   cout << "Vector v2 contains following elements" << endl;

   for (auto it = v2.begin(); it != v2.end(); ++it)
      cout << *it << endl;

   return 0;
}

Let us compile and run the above program, this will produce the following result −

Vector v2 contains following elements
1
2
3
4
5