How to implement standard iterators in class

Question

I have classes which are usually using standard containers as underlying fields. For example, I have a class

template 
class Vec_3D
{
public:
          


        

Answer 1

A range-based for loop only requires that your class have begin() and end() methods (or overloads of std::begin() and std::end()) that return iterators. It doesn't care where those iterators come from. So, the simplest solution is to just use the array's own iterators instead of trying to define your own, eg:

template 
class Vec_3D
{
public:
    typedef typename std::array array_type;
    typedef typename array_type::iterator iterator;
    typedef typename array_type::const_iterator const_iterator;
    // or:
    // using array_type = std::array;
    // using iterator = array_type::iterator;
    // using const_iterator = array_type::const_iterator;
    ...

    inline iterator begin() noexcept { return vec.begin(); }
    inline const_iterator cbegin() const noexcept { return vec.cbegin(); }
    inline iterator end() noexcept { return vec.end(); }
    inline const_iterator cend() const noexcept { return vec.cend(); }
    ...

private:
    array_type vec;
};