Iterator concept describes types that can be used to identify and traverse the elements of a container.
Iterator is the base concept used by other iterator types:
RandomAccessIterator. Iterators can be thought of as an abstraction of pointers.
The following expressions must be valid and have their specified effects:
r is dereferenceable (see below)
r is incrementable (the behavior of the expression ++r is defined)
Iterators for which the behavior of the expression *i is defined are called dereferenceable.
Iterators are not dereferenceable if
- they are past-the-end iterators (including pointers past the end of an array) or before-begin iterators. Such iterators may be dereferenceable in a particular implementation, but the library never assumes that they are.
- they are singular iterators, that is, iterators that are not associated with any sequence. A null pointer, as well as a default-constructed pointer (holding an indeterminate value) is singular
- they were invalidated by one of the iterator-invalidating operations on the sequence to which they refer.
|| specifies that objects of a type can be incremented and dereferenced |