SGI

random_access_iterator<T Distance>

Category: iterators Component type: type

Description

Random_access_iterator is an iterator base class: it is intended that an iterator that is a model of Random Access Iterator and whose value type and distance type are T and Distance may be defined by inheriting from random_access_iterator<T Distance> [1]. Random_access_iterator is entirely empty: it has no member functions member variables or nested types. It exists solely to simplify the definition of the functions iterator_category distance_type and value_type.

Example

class my_random_access_iterator : public random_access_iterator<double>
{
  ...
};
This declares my_random_access_iterator to be a Random Access Iterator whose value type is double and whose distance type is ptrdiff_t. If Iter is an object of class my_random_access_iterator then iterator_category(Iter) will return random_access_iterator_tag() value_type(Iter) will return (double*) 0 and distance_type(Iter) will return (ptrdiff_t*) 0.

Definition

Defined in the standard header iterator and in the nonstandard backward-compatibility header iterator.h. This class is no longer part of the C++ standard although it was present in early drafts of the standard. It is retained in this implementation for backward compatibility.

Template parameters

Parameter Description Default
T The iterator's value type  
Distance The iterator's distance type ptrdiff_t

Model of

Assignable

Public base classes

None

Type requirements

The distance type must be a signed integral type.

Public base classes

None.

Members

None.

New Members

None.

Notes

[1] It is not required that a Random Access Iterator inherit from the base random_access_iterator. It is however required that the functions iterator_category distance_type and value_type be defined for every Random Access Iterator. (Or if you are using the iterator_traits mechanism that iterator_traits is properly specialized for every Random Access Iterator.) Since those functions are defined for the base random_access_iterator the easiest way to ensure that are defined for a new type is to derive that class from random_access_iterator and rely on the derived-to-base standard conversion of function arguments.

See also

The Iterator Tags overview iterator_traits iterator_category value_type distance_type input_iterator output_iterator forward_iterator bidirectional_iterator
[Silicon Surf] [STL Home]
Copyright © 1999 Silicon Graphics Inc. All Rights Reserved. TrademarkInformation