One Minute Evaluations for 7-9 October

CS 509 - Advanced Programming II

• Topic: We discussed exception handling, how to declare exceptions, how and when to catch, what exceptions are, what are necessary exceptions, and iterators, different types of iterators.

  Question: Is typedef vector<iterator> itvec a valid declaration?

  One minute response: Not quite, because iterators can only be declared relative to a container type. You would need something like

   typedef std::vector<int>       ivec;
   typedef ivec::iterator         ivec_iter;
   typedef std::vector<ivec_iter> iveciter_vec;
   
   iveciter_vec odd_elements; 

  This is, however, exceptionally dangerous programming, because the iterators in odd_elements are almost certainly going to be invalidated over time, and you have no way of recognizing when that happens.

• Topic: I learned that I can probably circumvent using exceptions in virtually every application I'll encounter and still feel confident that I'm not taking the easy way out.

  Question: Would it be feasable to write code to implement unsupported operators in certain iterator types and make algorithm writing easier?

  One minute response: It would, but you would be producing non-standard extensions to the library. Whether this should bother you or not is a harder question to answer.

• Topic: Iterators, STL lists, vectors , exceptions.

• Topic: Exceptions, iterators.

• Question: Why do I have to learn about forward, bidirectional iterators when I cannot declare them in my code? What is iterator invalidation?

  One minute response: You declare generic iterators; containers provide specific ones. If you don't understand the difference between, say, bidirectional and random iterators, you'll become confused when you try to use an unsupported opration on the wrong iterator. Iterator invalidation is the analog to the dangling pointer problem.

• Topic: Exceptions and iterators.

  Question: Does each element in a container have an iterator [?].

  One minute response: Yes; and also, the phanotm elements at either end of a container also have iterators (end and rend).

• Topic: Exception handling, containers, iterators.

• Topic: Exceptions, exception examples, and iterators in today's class.

• Topic: This week we covered all the exceptions and we also covered the iterators.

• Topic: Exceptions, iterators, iterator invalidation.

• Topic: We talked about iterators, the dangers of iterators, as well as their usefulness.

  Question: Is it a good idea to iterate through all elements of vectors of vectors uing two iterators, one for the smaller or internal vector, and one for the bigger one? What should I keep in mind if I decide to use that?

  One minute response: With only one minute to answer, I don't want to get into whether or not it's a good idea, but you certainly can do it. I suspect that, if it were me, I would look for a diffent algorithm, one that wouldn't require that I do O(n²) work.

This page last modified on 16 July 2003.