C++ 算法 中的 copy_backward函数

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

#include <iostream>     
#include <algorithm>    
#include <vector>       
int main () 
{ std::vector<int> newvector;
  for (int k=1; k<=5; k++)
  newvector.push_back(k*5);          
  newvector.resize(newvector.size()+3);  
  std::copy_backward ( newvector.begin(), newvector.begin()+5, newvector.end() );
  std::cout << "newvector contains:";
  for (std::vector<int>::iterator ti=newvector.begin(); ti!=newvector.end(); ++ti)
  std::cout << ' ' << *ti;
  std::cout << '\n';
  return 0;
}