Iterator
An iterator that reads, writes, and allows random access to a container.
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NOTE:For a complete discussion of iterators, see the Iterators section of this reference.
Iterators are a generalization of pointers that allow a C++ program to uniformly interact with different data structures. Random access iterators can read, write, and allow random access to the containers they serve. These iterators satisfy the requirements listed below.
The following key pertains to the iterator requirements listed below:
| a and b | values of type X |
| n | value of distance type |
| u, Distance, tmp and m | identifiers |
| r | value of type X& |
| t | value of type T |
The following expressions must be valid for random access iterators:
| X u | u might have a singular value |
| X() | X() might be singular |
| X(a) | copy constructor, a == X(a) |
| X u(a) | copy constructor, u == a |
| X u = a | assignment, u == a |
| a == b, a != b | return value convertible to bool |
| r = a | assignment, r == a |
| *a | return value convertible to T& |
| a->m | equivalent to (*a).m |
| ++r | returns X& |
| r++ | return value convertible to const X& |
| *r++ | returns T& |
| --r | returns X& |
| r-- | return value convertible to const X& |
| *r-- | returns T& |
| r += n | Semantics of --r or ++r n times depending on the sign of n |
| a + n, n + a | returns type X |
| r -= n | returns X&, behaves as r += -n |
| a - n | returns type X |
| b - a | returns distance |
| a[n] | *(a+n), return value convertible to T |
| a < b | total ordering relation |
| a > b | total ordering relation opposite to < |
| a <= b | !(a < b) |
| a >= b | !(a > b) |
Like forward iterators, random access iterators have the condition that a == b implies *a == *b.
There are no restrictions on the number of passes an algorithm may make through the structure.
All relational operators return a value convertible to bool.
Iterators, Forward Iterators, Bidirectional Iterators