Question

I am currently working on creating a header file that acts like the standard library. I am in the progress of implemeing .end() for my linked list. In my cpp file I have an integer pointer which is expected to recieve the value of the .end() like

int* itrend;
itrend = ca.end();

ca is just an instance of my object in my header file.
In my hpp file, I have a list iterator going to my listofvalues.end(). I would like to return the .end() value like

int* end() 
{
    std::list<value_type>::iterator i = listOfValues.end();
    return (&*i);

}

My “List of values” is just a list holding several ints. eg

[1,2,3,4,5,6,7,8,9]

In my hpp file, I have a list iterator going to my listofvalues.end(). I would like to return the .end() value (which returns a list iterator); now this posess a problem that it returns the list iterator when I want to have an integer pointer. I have tried to deference it and take the address by using &* and this will give an error saying “List Iterator Not Dereferencable”. I know it’s because I’m trying to get the element after the last value, but that is exactly what I need to return, since I am trying to re-implement the linked list .end() method.

Does anyone know how I can have an integer pointer point to the List.end()?

Any assistance is appreciated.

Answer 1

To implement begin() and end() in a style similar to STL return iterators, not pointers:

template <typename value_type>
class my_list
{
public:
    typedef std::list<value_type>::iterator iterator;
    typedef std::list<value_type>::const_iterator const_iterator;

    iterator begin() { return listofValues.begin(); }
    const_iterator begin() const { return listofValues.begin(); }


    iterator end() { return listofValues.end(); }
    const_iterator end() const { return listofValues.end(); }
};