template<class InputIterator>
  typename iterator_traits<InputIterator>::difference_type
    distance (InputIterator first, InputIterator last);

<iterator>

Return distance between iterators

Calculates the number of elements between first and last.

If i is a Random Access Iterator, the function uses operator- to calculate this. Otherwise, the function uses repeatedly the increase or decrease operator (operator++ or operator--) until this distance is calculated.

Parameters

first

Iterator pointing to the initial element.

second

Iterator pointing to the final element. This must be reachable from first.

Return value

Example

// distance example
#include <iostream>
#include <iterator>
#include <list>
using namespace std;

int main () {
  list<int> mylist;
  for (int i=0; i<10; i++) mylist.push_back (i*10);

  list<int>::iterator first = mylist.begin();
  list<int>::iterator last = mylist.end();

  cout << "The distance is: " << distance(first,last) << endl;

  return 0;
}

Output

The distance is: 10

Complexity

See also