#include <iostream>  // std::cout
#include <vector>    // std::vector, std::next

namespace{
   int N = 100;
}

/*
 * example for iterating over the elements of an STL container
 */
int main()
{
   std::vector<int> v{};
   for(int i = 1; i <= N; i++) v.push_back(i);
   
   // 1)
   // using an explicit iterator type
   int sum = 0;
   for(std::vector<int>::iterator j = v.begin(); j != v.end(); j = std::next(j))
      sum += *j;
   std::cout << sum << "\n";
   
   // 2)
   // implicit typing with auto - this is a common use case for "auto"
   sum = 0;
   for(auto j = v.begin(); j != v.end(); j = std::next(j))
      sum += *j;
   std::cout << sum << "\n";
   
   // 3)
   // more recently introduced syntax; note that this copies the values into "i"
   sum = 0;
   for(int i: v) sum += i;
   std::cout << sum << "\n";
}