boost relocate function, what is the effect?

Question

What does relocate() mean in boost multi-index container?

I have read the manual from boost documentations, but I want to see a simple example and see the difference of using and not using the relocate function. The examples on the web are not simple though....

Answer 1

It merely relocates (moves) item(s) in a sequenced index:

#include <boost/multi_index_container.hpp>
#include <boost/multi_index/sequenced_index.hpp>
#include <iostream>

using namespace boost::multi_index;

typedef multi_index_container<
  int,
  indexed_by<sequenced<> > 
> Ints;


int main() 
{ 
  Ints ints;
  ints.insert(ints.end(), 1);
  ints.insert(ints.end(), 2);
  ints.insert(ints.end(), 3);
  ints.insert(ints.end(), 4);
  std::for_each (ints.begin(), ints.end(), [&](int i) { std::cout << i << std::endl; }); // 1, 2, 3, 4

  auto i = find(ints.begin(), ints.end(), 2);
  ints.relocate(ints.end(), i);
  std::for_each (ints.begin(), ints.end(), [&](int i) { std::cout << i << std::endl; }); // 1, 3, 4, 2
}