data-structures/cpp/iterator.cpp

#include <iostream>
#include <forward_list>
#include <vector>

int main() {
  std::vector<std::string> vec { "Lewis Hamilton", "Lewis Hamilton", "Nico Roseberg", "Sebastain Vettel", "Lewis Hamilton", "Sebastain Vettel", "Sebastain Vettel", "Sebastain Vettel", "Fernando Alonso" };

  auto it { vec.begin() };  // Constant time
  std::cout << "Latest winner is: " << *it << std::endl;

  it += 8;  // Constant time
  std::cout << "Winner before 8 years was: " << *it << std::endl;

  std::advance(it, -3); // Contant time
  std::cout << "Winner before 3 years of that was: " << *it << std::endl;

  std::forward_list<std::string> fwd { vec.begin(), vec.end() };

  auto it1 { fwd.begin() };
  std::cout << "Latest winner is: " << *it1 << std::endl;

  std::advance(it1, 5); // Time taken is proportional to the number of elements
  
  std::cout << "Winner before 5 years was: " << *it1 << std::endl;

  // Going back will result in compilr time error as forward_list only allows us to move towards the end.
  // std::advance(it1, -2); // Compiler error

  return 0;
}