access to nth element of set

Question

There is a set visited. And I wanna check all its elements from 4-th to last. I'm trying to do something like that

int visited_pointer = 4;
for ( set<int>::iterator i_visited=visited.begin()+visited_pointer
    ; i_visited!=visited.end()
    ; i_visited++
)

and got errors with operator+.

How can I do that in the right way?

Answer 1

That usage of operator+ is only provided for random-access iterators. set iterators are bi-directional iterators.

But the function std::advance can be used to move any iterator a certain number of places:

#include <iterator>

//...

set<int>::iterator i_visited = visited.begin();
for ( std::advance(i_visited, visited_pointer)
    ; i_visited!=visited.end()
    ; ++i_visited
)