A collection class is a class that can contain a number of items in a certain data structure and perform operations on the contained items; insert, remove, find etc. ... QList ; a doubly linked list structure. ... An iterator is a class for safely traversing the items in a collection: . ... Qt has an array template class, QArray , which stores the items directly in the array. ... We discuss QList here, but the same applies for all collection classes and all collection class iterators. ... Classes: . ...