7. Iterators
On the one hand iterators are generalisations of pointers which represents positions in a container. On the other hand, they provide powerful iteration and random access in a container.
Iterators are the glue between the generic containers and the generic algorithms of the Standard Template Library.
Iterators support the following operations:
- *
- Returns the element at the current position.
- ==, !=
- Compares two positions.
- =
- Assigns a new value to an iterator.
The range-based for-loop uses the iterators implicitly.
Because iterators are not checked, they have the same issues as pointers.
std::vector<int> verc{1, 23, 3, 3, 3, 4, 5};
std::deque<int> deq;
// Start iterator bigger than end iterator
std::copy(vec.begin()+2, vec.begin(), deq.begin());
// Target container too small
std::copy(vec.begin(), vec.end(), deq.end());