STL_advance distance prev next

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

Return distance between iterators

Calculates the number of elements between first and last.

 // advance example
 #include <iostream>     // std::cout
 #include <iterator>     // std::distance
 #include <list>         // std::list

 int main () {
   std::list<int> mylist;
   ; i<; i++) mylist.push_back (i*);

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

   std::cout << "The distance is: " << std::distance(first,last) << '\n';

   ;
 }

template <class InputIterator, class Distance>
  void advance (InputIterator& it, Distance n);

Advance iterator

Advances the iterator it by n element positions.

Return value

none

 // advance example
 #include <iostream>     // std::cout
 #include <iterator>     // std::advance
 #include <list>         // std::list

 int main () {
   std::list<int> mylist;
   ; i<; i++) mylist.push_back (i*);

   std::list<int>::iterator it = mylist.begin();

   std::advance (it,);

   std::cout << "The sixth element in mylist is: " << *it << '\n';

   ;
 }

Output:

The sixth element in mylist is: 50

template <class ForwardIterator>
  ForwardIterator next (ForwardIterator it,
       typename iterator_traits<ForwardIterator>::difference_type n = 1);

Get iterator to next element

Returns an iterator pointing to the element that it would be pointing to if advanced n positions.

 // next example
 #include <iostream>     // std::cout
 #include <iterator>     // std::next
 #include <list>         // std::list
 #include <algorithm>    // std::for_each

 int main () {
   std::list<int> mylist;
   ; i<; i++) mylist.push_back (i*);

   std::cout << "mylist:";
   std::for_each (mylist.begin(),
                  std::next(mylist.begin(),),
                  [](int x) {std::cout << ' ' << x;} );

   std::cout << '\n';

   ;
 }

Output:

mylist: 0 10 20 30 40

template <class BidirectionalIterator>
  BidirectionalIterator prev (BidirectionalIterator it,
       typename iterator_traits<BidirectionalIterator>::difference_type n = 1);

Get iterator to previous element

Returns an iterator pointing to the element that it would be pointing to if advanced -n positions.

Return value

An iterator to the element n positions before it.

 // prev example
 #include <iostream>     // std::cout
 #include <iterator>     // std::next
 #include <list>         // std::list
 #include <algorithm>    // std::for_each

 int main () {
   std::list<int> mylist;
   ; i<; i++) mylist.push_back (i*);

   std::cout << "The last element is " << *std::prev(mylist.end()) << '\n';

   ;
 }

Output:

The last element is 90