C++ Primer Plus

Iterator Hierarchy

You have probably noticed that the iterator kinds form a hierarchy. A forward iterator has all the capabilities of an input iterator and of an output iterator, plus its own capabilities. A bidirectional iterator has all the capabilities of a forward iterator, plus its own capabilities. And a random access iterator has all the capabilities of a forward iterator, plus its own capabilities. Table 16.4 summarizes the main iterator capabilities. In it, i is an iterator, and n is an integer.

Table 16.4. Iterator Capabilities

An algorithm written in terms of a particular kind of iterator can use that kind of iterator or any other iterator ...