| Value type | X::value_type | The type of the object stored in a Collection. If the Collection is mutable then the value type must be Assignable. Otherwise the value type must be CopyConstructible. |
| Iterator type | X::iterator | The type of iterator used to iterate through a Collection's elements. The iterator's value type is expected to be the Collection's value type. A conversion from the iterator type to the const iterator type must exist. The iterator type must be an InputIterator. |
| Const iterator type | X::const_iterator | A type of iterator that may be used to examine, but not to modify, a Collection's elements. |
| Reference type | X::reference | A type that behaves like a reference to the Collection's value type. [1] |
| Const reference type | X::const_reference | A type that behaves like a const reference to the Collection's value type. |
| Pointer type | X::pointer | A type that behaves as a pointer to the Collection's value type. |
| Distance type | X::difference_type | A signed integral type used to represent the distance between two of the Collection's iterators. This type must be the same as the iterator's distance type. |
| Size type | X::size_type | An unsigned integral type that can represent any nonnegative value of the Collection's distance type. |
| X | A type that is a model of Collection. |
| a, b | Object of type X. |
| T | The value type of X. |
| Name | Expression | Return type |
|---|---|---|
| Beginning of range | a.begin() | iterator if a is mutable, const_iterator otherwise |
| End of range | a.end() | iterator if a is mutable, const_iterator otherwise |
| Size | a.size() | size_type | Empty Collection | a.empty() | Convertible to bool |
| Name | Expression | Semantics | Postcondition |
|---|---|---|---|
| Beginning of range | a.begin() | Returns an iterator pointing to the first element in the Collection. | a.begin() is either dereferenceable or past-the-end. It is past-the-end if and only if a.size() == 0. |
| End of range | a.end() | Returns an iterator pointing one past the last element in the Collection. | a.end() is past-the-end. |
| Size | a.size() | Returns the size of the Collection, that is, its number of elements. | a.size() >= 0 |
| Empty Collection | a.empty() | Equivalent to a.size() == 0. (But possibly faster.) | |
size() is at most linear in the Collection's size. empty() is amortized constant time.
| Valid range | For any Collection a, [a.begin(), a.end()) is a valid range. |
| Range size | a.size() is equal to the distance from a.begin() to a.end(). |
| Completeness | An algorithm that iterates through the range [a.begin(), a.end()) will pass through every element of a. |
[1] The reference type does not have to be a real C++ reference. The requirements of the reference type depend on the context within which the Collection is being used. Specifically it depends on the requirements the context places on the value type of the Collection. The reference type of the Collection must meet the same requirements as the value type. In addition, the reference objects must be equivalent to the value type objects in the collection (which is trivially true if they are the same). Also, in a mutable Collection, an assignment to the reference object must result in an assignment to the object in the Collection (again, which is trivially true if they are the same object, but non-trivial if the reference type is a proxy class).
| Copyright © 2000 | Jeremy Siek, Univ.of Notre Dame and C++ Library & Compiler Group/SGI (jsiek@engr.sgi.com) |
| Copyright © 2004 | Thorsten Ottosen. |