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Concept InputIterator

InputIterator

Description

An input iterator is an iterator that can read through a sequence of values. It is single-pass (old values of the iterator cannot be re-used), and read-only.

An input iterator represents a position in a sequence. Therefore, the iterator can point into the sequence (returning a value when dereferenced and being incrementable), or be off-the-end (and not dereferenceable or incrementable).

Refinement of

Associated types

  • value_type

    std::iterator_traits<Iter>::value_type

    The value type of the iterator (not necessarily what *i returns)

  • difference_type

    std::iterator_traits<Iter>::difference_type

    The difference type of the iterator

  • category

    std::iterator_traits<Iter>::iterator_category

    The category of the iterator

Notation

Iter
A type playing the role of iterator-type in the InputIterator concept.
i, j
Objects of type Iter
x
Object of type value_type

Type expressions

Category tag

category must be derived from std::input_iterator_tag, a model of DefaultConstructible, and a model of CopyConstructible.

Value type copy constructibility

value_type must be a model of CopyConstructible.

Difference type properties

difference_type must be a model of SignedInteger.

Valid expressions

Name Expression Type Precondition Semantics Postcondition

Dereference

*i

Convertible to value_type

i is incrementable (not off-the-end)

 ? ?

Preincrement

++i

Iter &

i is incrementable (not off-the-end)

 ? ?

Postincrement

i++

i is incrementable (not off-the-end)

Equivalent to (void)(++i)

i is dereferenceable or off-the-end

Postincrement and dereference

*i++

Convertible to value_type

i is incrementable (not off-the-end)

Equivalent to {value_type t = *i; ++i; return t;}

i is dereferenceable or off-the-end

Complexity

All iterator operations must take amortized constant time.

Models

  • std::istream_iterator

See also

Copyright ? 2001, 2002 Indiana University
Copyright ? 2000, 2001 University of Notre Dame du Lac
Copyright ? 2000 Jeremy Siek, Lie-Quan Lee, Andrew Lumsdaine
Copyright ? 1996-1999 Silicon Graphics Computer Systems, Inc.
Copyright ? 1994 Hewlett-Packard Company

This product includes software developed at the University of Notre Dame and the Pervasive Technology Labs at Indiana University. For technical information contact Andrew Lumsdaine at the Pervasive Technology Labs at Indiana University. For administrative and license questions contact the Advanced Research and Technology Institute at 351 West 10th Street. Indianapolis, Indiana 46202, phone 317-278-4100, fax 317-274-5902.

Some concepts based on versions from the MTL draft manual and Boost Graph and Property Map documentation, the SGI Standard Template Library documentation and the Hewlett-Packard STL, under the following license:

Permission to use, copy, modify, distribute and sell this software and its documentation for any purpose is hereby granted without fee, provided that the above copyright notice appears in all copies and that both that copyright notice and this permission notice appear in supporting documentation. Silicon Graphics makes no representations about the suitability of this software for any purpose. It is provided "as is" without express or implied warranty.
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