Question

I’m trying to do this:

typedef std::map<std::string, time_t> my_map;
const mymap& some_function();

class bla
{
private:
  my_map::iterator current
  bla(const mymap& m) : current(m.begin())
  {   }
}

And it’s not working. The somewhat more convoluted real error message is:

error: no matching function for call to ‘std::_Rb_tree_iterator, long int> >::_Rb_tree_iterator(std::map, long int>::const_iterator)’

I tried moving the initialization/assignment to the constructor body:

{ current = m.begin(); }

Which didn’t work either. So I thought, the type of current is wrong, so I just let the compiler deduce that:

...
   decltype(my_map::begin()) current;
...

Which doesn’t work either.

All I need is an iterator member that is set at bla construction time, so I don’t have to explicitly set it in some stupid extra function and can iterate over the map externally through:

bool bla::do_stuff(...output...)
{ 
    if(current = m.end())
        return false;
    balblabla(current);
    ++current;
    return true;
}

Answer 1

You’re trying to assign const_iterator to iterator. There are two solutions:

1. Take map by non-const reference (bla(my_map& m) : current(m.begin()) {}).
2. Change the member type to const_iterator.