Use String reverse iterator and iterator as same type of object (C++)

Question

I am trying to use the same variable for both iterator and reverse iterator. However, I cannot find the common base class to do so. I want to do something like this:

string a;
....
string::iterator i;
if (....)
    i = a.begin();
else
    i = a.rbegin();  //Error
....

Is there a good way of doing this?

There is no requirement that iterator and reverse_iterator be of compatible types. They are not necessarily classes either, so may not have a common base. Try do have characteristics/traits in common though. — Peter
– Peter, Commented Apr 30, 2018 at 10:53

Caleth · Accepted Answer · 2018-04-30 10:55:08Z

7

There is no common type for std::string::iterator and std::string::reverse_iterator.

If you want to choose between them, you will need to have a different function for each type. The simplest way to do that is with a template

E.g.

template <typename Iterator>
void do_stuff(Iterator begin, Iterator end)
{
    ...
}

int main()
{
    string a;
    if (...)
        do_stuff(a.begin(), a.end());
    else
        do_stuff(a.rbegin(), a.rend());
    return 0;
}

answered Apr 30, 2018 at 10:55

Caleth

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