How to keep track of current and previous iterator on a c++ vector?

Question

I have one vector container and I would like to make a subtraction operation on the values of its content using the current iterator against the previous iterator, any help will be much appreciated

Answer 1

vector<MyClass>::iterator itPrevious = my_vec.begin();
vector<MyClass>::iterator itCurrent = itPrevious;
if (itCurrent != my_vec.end())
{
    for (++itCurrent;  itCurrent != my_vec.end();  ++itCurrent)
    {
        // do something with itPrevious and itCurrent
        itPrevious = itCurrent;
    }
}