typedef T value_type;
typedef T& reference;
typedef const T& const_reference;
typedef long size_type;
typedef size_type difference_type;

typedef std::vectory<double> MyGreatArray;
//Do stuff with MyGreatArray
//What is the type inside MyGreatArray? I want to assign a single element
MyGreatArray::value_type one_element; //now one_element is a double!
MyGreatArray::iterator MyGreatArrayIt; //now this is an iterator vector<double>
one_element = 1.0;