Question

When I have a template class which contains template map and a const_iterator declared as in the following code by typedef, how can I iterate through the elements of the map outside the class, f.e in main to print them on the output?

template<class K, class V>
class template_map{
private:

    typedef typename std::map<K,V> TMap;
    TMap my_map;

public:
    typedef typename TMap::const_iterator const_iterator;
    ...
};

int main()
{

template_Map<int,double> Map1 //suppose that contains elements

?
}

Update: Can the typedef iterator be used outside the class? If yes in what way?

Answer 1

You need to define member functions on your template that would return iterators:

template<class K, class V>
class template_map{

private:

typedef typename std::map<K,V> TMap;
TMap my_map;

public:
    typedef typename TMap::const_iterator const_iterator;
    const_iterator begin() const { return my_map.begin(); }
    const_iterator end() const   { return my_map.end(); }
};

Then:

int main()
{
    template_map<int, int> m;
    // Populate map...

    // Then iterate...
    for (auto i = m.begin(); i != m.end(); i++)
    {
    }
}

However, I am unsure what your adding to std::map here, why not just use it as is?