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			HTML
		
	
	
	
	
	
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| "text/html; charset=us-ascii" />
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| <link rel="stylesheet" href="../../../../boost.css" type="text/css"/>
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| <script type="text/javascript" src="js/jquery.toc-gw.js" async="async" ></script>
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| <title>Iterator Concepts</title>
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| </head>
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| <body>
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| <h1><img src="../../../../boost.png" align="middle" />Iterator Concepts</h1>
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| <div class="toc" id="toc"></div>
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| <p>An Iterator is a restricted pointer-like object pointing into a
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| vector or matrix container.</p>
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| <h2><a name="indexed_bidirectional_iterator" 
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| ></a>Indexed Bidirectional Iterator</h2>
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| <h4>Description</h4>
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| <p>An Indexed Bidirectional Iterator is an iterator of a container
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| that can be dereferenced, incremented, decremented and carries
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| index information.</p>
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| <h4>Refinement of</h4>
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| <p>Assignable, Equality Comparable, Default Constructible.</p>
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| <h4>Associated types</h4>
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| <table border="1" summary="associated types">
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| <tbody>
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| <tr>
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| <td>Value type</td>
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| <td>The type of the value obtained by dereferencing a Indexed
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| Bidirectional Iterator</td>
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| </tr>
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| <tr>
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| <td>Container type</td>
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| <td>The type of the container a Indexed Bidirectional Iterator
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| points into.</td>
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| </tr>
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| </tbody>
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| </table>
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| <h4>Notation</h4>
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| <table border="0" summary="notation">
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| <tbody>
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| <tr>
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| <td><code>I</code></td>
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| <td>A type that is a model of Indexed Bidirectional Iterator</td>
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| </tr>
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| <tr>
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| <td><code>T</code></td>
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| <td>The value type of <code>I</code></td>
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| </tr>
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| <tr>
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| <td><code>C</code></td>
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| <td>The container type of <code>I</code></td>
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| </tr>
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| <tr>
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| <td><code>it</code>, <code>itt, it1</code>, <code>it2</code></td>
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| <td>Objects of type <code>I</code></td>
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| </tr>
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| <tr>
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| <td><code>t</code></td>
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| <td>Object of type <code>T</code></td>
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| </tr>
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| <tr>
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| <td><code>c</code></td>
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| <td>Object of type <code>C</code></td>
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| </tr>
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| </tbody>
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| </table>
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| <h4>Definitions</h4>
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| <p>A Indexed Bidirectional Iterator may be <i>mutable</i>, meaning
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| that the values referred to by objects of that type may be
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| modified, or <i>constant</i> , meaning that they may not. If an
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| iterator type is mutable, this implies that its value type is a
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| model of Assignable; the converse, though, is not necessarily
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| true.</p>
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| <p>A Indexed Bidirectional Iterator may have a <i>singular</i>
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| value, meaning that the results of most operations, including
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| comparison for equality, are undefined. The only operation that is
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| guaranteed to be supported is assigning a nonsingular iterator to a
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| singular iterator.</p>
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| <p>A Indexed Bidirectional Iterator may have a
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| <i>dereferenceable</i> value, meaning that dereferencing it yields
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| a well-defined value. Dereferenceable iterators are always
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| nonsingular, but the converse is not true.</p>
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| <p>An Indexed Bidirectional Iterator is <i>past-the-end</i> if it
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| points beyond the last element of a container. Past-the-end values
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| are nonsingular and nondereferenceable.</p>
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| <h4>Valid expressions</h4>
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| <p>In addition to the expressions defined for Assignable, Equality
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| Comparable and Default Constructible, the following expressions
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| must be valid.</p>
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| <table border="1" summary="expressions">
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| <tbody>
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| <tr>
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| <th>Name</th>
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| <th>Expression</th>
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| <th>Type requirements</th>
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| <th>Return type</th>
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| </tr>
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| <tr>
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| <td>Default constructor</td>
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| <td><code>I it</code></td>
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| <td> </td>
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| <td> </td>
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| </tr>
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| <tr>
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| <td>Dereference</td>
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| <td><code>*it</code></td>
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| <td> </td>
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| <td>Convertible to <code>T</code>.</td>
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| </tr>
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| <tr>
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| <td>Dereference assignment</td>
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| <td><code>*it = t</code></td>
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| <td><code>I</code> is mutable.</td>
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| <td> </td>
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| </tr>
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| <tr>
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| <td>Member access</td>
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| <td><code>it->m</code></td>
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| <td><code>T</code> is a type for which <code>t.m</code> is
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| defined.</td>
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| <td> </td>
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| </tr>
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| <tr>
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| <td>Preincrement</td>
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| <td><code>++ it</code></td>
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| <td> </td>
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| <td><code>I &</code></td>
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| </tr>
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| <tr>
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| <td>Postincrement</td>
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| <td><code>it ++</code></td>
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| <td> </td>
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| <td><code>I</code></td>
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| </tr>
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| <tr>
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| <td>Predecrement</td>
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| <td><code>-- it</code></td>
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| <td> </td>
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| <td><code>I &</code></td>
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| </tr>
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| <tr>
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| <td>Postdecrement</td>
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| <td><code>it --</code></td>
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| <td> </td>
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| <td><code>I</code></td>
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| </tr>
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| <tr>
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| <td>Index</td>
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| <td><code>it.index ()</code></td>
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| <td> </td>
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| <td><code>C::size_type</code></td>
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| </tr>
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| </tbody>
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| </table>
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| <h4>Expression Semantics</h4>
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| <p>Semantics of an expression is defined only where it differs
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| from, or is not defined in, Assignable, Equality Comparable and
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| Default Constructible.</p>
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| <table border="1" summary="semantics">
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| <tbody>
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| <tr>
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| <th>Name</th>
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| <th>Expression</th>
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| <th>Precondition</th>
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| <th>Semantics</th>
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| <th>Postcondition</th>
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| </tr>
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| <tr>
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| <td>Default constructor</td>
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| <td><code>I it</code></td>
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| <td> </td>
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| <td> </td>
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| <td><code>it</code> is singular.</td>
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| </tr>
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| <tr>
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| <td>Dereference</td>
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| <td><code>*it</code></td>
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| <td><code>it</code> is dereferenceable.</td>
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| <td> </td>
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| <td> </td>
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| </tr>
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| <tr>
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| <td>Dereference assignment</td>
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| <td><code>*it = t</code></td>
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| <td>Same as for <code>*it</code>.</td>
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| <td> </td>
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| <td><code>*it</code> is a copy of t.</td>
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| </tr>
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| <tr>
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| <td>Member access</td>
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| <td><code>it->m</code></td>
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| <td><code>it</code> is dereferenceable.</td>
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| <td>Equivalent to <code>(*it).m</code></td>
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| <td> </td>
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| </tr>
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| <tr>
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| <td>Preincrement</td>
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| <td><code>++ it</code></td>
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| <td><code>it</code> is dereferenceable.</td>
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| <td><code>it</code> is modified to point to the next element.</td>
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| <td><code>it</code> is dereferenceable or past-the-end.
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| <code><br />
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| &it == &++ it</code>.<br />
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| If <code>it1 == it2</code>,<br />
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| then <code>++ it1 == ++ it2</code>.</td>
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| </tr>
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| <tr>
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| <td>Postincrement</td>
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| <td><code>it ++</code></td>
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| <td>Same as for <code>++ it</code>.</td>
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| <td>Equivalent to<br />
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| <code>{<br />
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|  I itt = it;<br />
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|  ++ it;<br />
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|  return itt;<br />
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| }</code></td>
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| <td><code>it</code> is dereferenceable or past-the-end.</td>
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| </tr>
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| <tr>
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| <td>Predecrement</td>
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| <td><code>-- it</code></td>
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| <td><code>it</code> is dereferenceable or past-the-end.<br />
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| There exists a dereferenceable iterator <code>itt</code> such that
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| <code>it == ++ itt</code>.</td>
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| <td><code>it</code> is modified to point to the previous
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| element.</td>
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| <td><code>it</code> is dereferenceable.<br />
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| <code>&it = &-- it</code>.<br />
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| If <code>it1 == it2</code>,<br />
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| then <code>-- it1 == -- it2</code>.<br />
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| If <code>it2</code> is dereferenceable and <code>it1 ==
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| ++it2</code>,<br />
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| then <code>--it1 == it2</code>.</td>
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| </tr>
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| <tr>
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| <td>Postdecrement</td>
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| <td><code>it --</code></td>
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| <td>Same as for -- <code>it</code>.</td>
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| <td>Equivalent to<br />
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| <code>{<br />
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|  I itt = it;<br />
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|  -- it;<br />
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|  return itt;<br />
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| }</code></td>
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| <td><code>it</code> is dereferenceable. </td>
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| </tr>
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| <tr>
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| <td>Index</td>
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| <td><code>it.index ()</code></td>
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| <td><code>it</code> is dereferenceable.</td>
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| <td><code>it.index () >= 0</code><br />
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| and<br />
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| <code>it.index () < it ().size ()</code></td>
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| <td>If <code>it1 == it2</code>,<br />
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| then <code>it1.index () == it2.index ()</code>.<br />
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| If <code>it1 == it2</code>,<br />
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| then <code>it1.index () < (++ it2).index
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| ()</code>.<br />
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| If <code>it1 == it2</code>,<br />
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| then <code>it1.index () > (-- it2).index
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| ()</code>.</td>
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| </tr>
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| </tbody>
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| </table>
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| <h4>Complexity guarantees</h4>
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| <p>The complexity of operations on indexed bidirectional iterators
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| is guaranteed to be amortized constant time.</p>
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| <h4>Invariants</h4>
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| <table border="1" summary="invariants">
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| <tbody>
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| <tr>
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| <td>Identity</td>
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| <td><code>it1 == it2</code> if and only if <code>&*it1 ==
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| &*it2</code>.</td>
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| </tr>
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| <tr>
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| <td>Symmetry of increment and decrement</td>
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| <td>If <code>it</code> is dereferenceable, then <code>++ it;
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| --it;</code> is a null operation. Similarly, <code>-- it; ++
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| it;</code> is a null operation.</td>
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| </tr>
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| <tr>
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| <td>Relation between iterator index and container element
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| operator</td>
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| <td>If <code>it</code> is dereferenceable, <code>*it == it ()
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| (it.index ())</code>.</td>
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| </tr>
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| </tbody>
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| </table>
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| <h4>Models</h4>
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| <ul>
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| <li><code>sparse_vector::iterator</code></li>
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| </ul>
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| <h2><a name="indexed_random_access_iterator"
 | |
| ></a>Indexed Random Access Iterator</h2>
 | |
| <h4>Description</h4>
 | |
| <p>An Indexed Random Access Iterator is an iterator of a container
 | |
| that can be dereferenced, moved forward, moved backward and carries
 | |
| index information.</p>
 | |
| <h4>Refinement of</h4>
 | |
| <p>LessThanComparable, <a href=
 | |
| "#indexed_bidirectional_iterator">Indexed Bidirectional
 | |
| Iterator</a> .</p>
 | |
| <h4>Associated types</h4>
 | |
| <table border="1" summary="associated types">
 | |
| <tbody>
 | |
| <tr>
 | |
| <td>Value type</td>
 | |
| <td>The type of the value obtained by dereferencing a Indexed
 | |
| Random Access Iterator</td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Container type</td>
 | |
| <td>The type of the container a Indexed Random Access Iterator
 | |
| points into.</td>
 | |
| </tr>
 | |
| </tbody>
 | |
| </table>
 | |
| <h4>Notation</h4>
 | |
| <table border="0" summary="notation">
 | |
| <tbody>
 | |
| <tr>
 | |
| <td><code>I</code></td>
 | |
| <td>A type that is a model of Indexed Random Access Iterator</td>
 | |
| </tr>
 | |
| <tr>
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| <td><code>T</code></td>
 | |
| <td>The value type of <code>I</code></td>
 | |
| </tr>
 | |
| <tr>
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| <td><code>C</code></td>
 | |
| <td>The container type of <code>I</code></td>
 | |
| </tr>
 | |
| <tr>
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| <td><code>it</code>, <code>itt, it1</code>, <code>it2</code></td>
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| <td>Objects of type <code>I</code></td>
 | |
| </tr>
 | |
| <tr>
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| <td><code>t</code></td>
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| <td>Object of type <code>T</code></td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td><code>n</code></td>
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| <td>Object of type <code>C::difference_type</code></td>
 | |
| </tr>
 | |
| </tbody>
 | |
| </table>
 | |
| <h4>Definitions</h4>
 | |
| <p>An Indexed Random Access Iterator <code>it1</code> is
 | |
| <i>reachable</i> from an Indexed Random Access Iterator
 | |
| <code>it2</code> if, after applying <code>operator ++</code> to
 | |
| <code>it2</code> a finite number of times, <code>it1 ==
 | |
| it2</code>.</p>
 | |
| <h4>Valid expressions</h4>
 | |
| <p>In addition to the expressions defined for <a href=
 | |
| "#indexed_bidirectional_iterator">Indexed Bidirectional
 | |
| Iterator</a> , the following expressions must be valid.</p>
 | |
| <table border="1" summary="expressions">
 | |
| <tbody>
 | |
| <tr>
 | |
| <th>Name</th>
 | |
| <th>Expression</th>
 | |
| <th>Type requirements</th>
 | |
| <th>Return type</th>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Forward motion</td>
 | |
| <td><code>it += n</code></td>
 | |
| <td> </td>
 | |
| <td><code>I &</code></td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Iterator addition</td>
 | |
| <td><code>it + n</code></td>
 | |
| <td> </td>
 | |
| <td><code>I</code></td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Backward motion</td>
 | |
| <td><code>i -= n</code></td>
 | |
| <td> </td>
 | |
| <td><code>I &</code></td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Iterator subtraction</td>
 | |
| <td><code>it - n</code></td>
 | |
| <td> </td>
 | |
| <td><code>I</code> </td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Difference</td>
 | |
| <td><code>it1 - it2</code></td>
 | |
| <td> </td>
 | |
| <td><code>C::difference_type</code></td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Element operator</td>
 | |
| <td><code>it [n]</code></td>
 | |
| <td> </td>
 | |
| <td>Convertible to <code>T</code>.</td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Element assignment</td>
 | |
| <td><code>it [n] = t</code></td>
 | |
| <td><code>I</code> is mutable</td>
 | |
| <td>Convertible to <code>T</code>.</td>
 | |
| </tr>
 | |
| </tbody>
 | |
| </table>
 | |
| <h4>Expression Semantics</h4>
 | |
| <p>Semantics of an expression is defined only where it differs
 | |
| from, or is not defined in, <a href=
 | |
| "#indexed_bidirectional_iterator">Indexed Bidirectional
 | |
| Iterator</a> .</p>
 | |
| <table border="1" summary="semantics">
 | |
| <tbody>
 | |
| <tr>
 | |
| <th>Name</th>
 | |
| <th>Expression</th>
 | |
| <th>Precondition</th>
 | |
| <th>Semantics</th>
 | |
| <th>Postcondition</th>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Forward motion</td>
 | |
| <td><code>it += n</code></td>
 | |
| <td>Including <code>it</code> itself, there must be <code>n</code>
 | |
| dereferenceable or past-the-end iterators following or preceding
 | |
| <code>it</code>, depending on whether <code>n</code> is positive or
 | |
| negative.</td>
 | |
| <td>If <code>n > 0</code>, equivalent to executing <code>++
 | |
| it</code> <code>n</code> times. If <code>n < 0</code>,
 | |
| equivalent to executing <code>-- it</code> <code>n</code> times. If
 | |
| <code>n == 0</code>, this is a null operation.</td>
 | |
| <td><code>it</code> is dereferenceable or past-the-end.</td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Iterator addition</td>
 | |
| <td><code>it + n</code></td>
 | |
| <td>Same as for <code>i += n</code>.</td>
 | |
| <td>Equivalent to<br />
 | |
| <code>{<br />
 | |
|  I itt = it;<br />
 | |
|  return itt += n;<br />
 | |
| }</code></td>
 | |
| <td>Result is dereferenceable or past-the-end.</td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Backward motion</td>
 | |
| <td><code>it -= n</code></td>
 | |
| <td>Including <code>it</code> itself, there must be <code>n</code>
 | |
| dereferenceable or past-the-end iterators preceding or following
 | |
| <code>it</code>, depending on whether <code>n</code> is positive or
 | |
| negative.</td>
 | |
| <td>Equivalent to <code>it += (-n)</code>.</td>
 | |
| <td><code>it</code> is dereferenceable or past-the-end.</td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Iterator subtraction</td>
 | |
| <td><code>it - n</code></td>
 | |
| <td>Same as for <code>i -= n</code>.</td>
 | |
| <td>Equivalent to<br />
 | |
| <code>{<br />
 | |
|  I itt = it;<br />
 | |
|  return itt -= n;<br />
 | |
| }</code></td>
 | |
| <td>Result is dereferenceable or past-the-end.</td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Difference</td>
 | |
| <td><code>it1 - it2</code></td>
 | |
| <td>Either <code>it1</code> is reachable from <code>it2</code> or
 | |
| <code>it2</code> is reachable from <code>it1</code>, or both.</td>
 | |
| <td>Returns a number <code>n</code> such that <code>it1 == it2 +
 | |
| n</code></td>
 | |
| <td> </td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Element operator</td>
 | |
| <td><code>it [n]</code></td>
 | |
| <td><code>it + n</code> exists and is dereferenceable.</td>
 | |
| <td>Equivalent to <code>*(it + n)</code></td>
 | |
| <td> </td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Element assignment</td>
 | |
| <td><code>i[n] = t</code></td>
 | |
| <td>Same as for <code>it [n]</code>.</td>
 | |
| <td>Equivalent to <code>*(it + n) = t</code></td>
 | |
| <td> </td>
 | |
| </tr>
 | |
| </tbody>
 | |
| </table>
 | |
| <h4>Complexity guarantees</h4>
 | |
| <p>The complexity of operations on indexed random access iterators
 | |
| is guaranteed to be amortized constant time.</p>
 | |
| <h4>Invariants</h4>
 | |
| <table border="1" summary="invariants">
 | |
| <tbody>
 | |
| <tr>
 | |
| <td>Symmetry of addition and subtraction</td>
 | |
| <td>If <code>it + n</code> is well-defined, then <code>it += n; it
 | |
| -= n;</code> and <code>(it + n) - n</code> are null operations.
 | |
| Similarly, if <code>it - n</code> is well-defined, then <code>it -=
 | |
| n; it += n;</code> and <code>(it - n) + n</code> are null
 | |
| operations.</td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Relation between distance and addition</td>
 | |
| <td>If <code>it1 - it2</code> is well-defined, then <code>it1 ==
 | |
| it2 + (it1 - it2)</code>.</td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Reachability and distance</td>
 | |
| <td>If <code>it1</code> is reachable from <code>it2</code>, then
 | |
| <code>it1 - it2 >= 0</code>.</td>
 | |
| </tr>
 | |
| </tbody>
 | |
| </table>
 | |
| <h4>Models</h4>
 | |
| <ul>
 | |
| <li><code>vector::iterator</code></li>
 | |
| </ul>
 | |
| <h2><a name="indexed_bidirectional_cr_iterator"
 | |
| ></a>Indexed Bidirectional Column/Row Iterator</h2>
 | |
| <h4>Description</h4>
 | |
| <p>An Indexed Bidirectional Column/Row Iterator is an iterator of a
 | |
| container that can be dereferenced, incremented, decremented and
 | |
| carries index information.</p>
 | |
| <h4>Refinement of</h4>
 | |
| <p>Assignable, Equality Comparable, Default Constructible.</p>
 | |
| <h4>Associated types</h4>
 | |
| <table border="1" summary="associated types">
 | |
| <tbody>
 | |
| <tr>
 | |
| <td>Value type</td>
 | |
| <td>The type of the value obtained by dereferencing a Indexed
 | |
| Bidirectional Column/Row Iterator</td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Container type</td>
 | |
| <td>The type of the container a Indexed Bidirectional Column/Row
 | |
| Iterator points into.</td>
 | |
| </tr>
 | |
| </tbody>
 | |
| </table>
 | |
| <h4>Notation</h4>
 | |
| <table border="0" summary="notation">
 | |
| <tbody>
 | |
| <tr>
 | |
| <td><code>I1</code></td>
 | |
| <td>A type that is a model of Indexed Bidirectional Column/Row
 | |
| Iterator</td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td><code>I2</code></td>
 | |
| <td>A type that is a model of Indexed Bidirectional Row/Column
 | |
| Iterator</td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td><code>T</code></td>
 | |
| <td>The value type of <code>I1</code> and <code>I2</code></td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td><code>C</code></td>
 | |
| <td>The container type of <code>I1</code> and <code>I2</code></td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td><code>it1</code>, <code>it1t, it11</code>,
 | |
| <code>it12</code></td>
 | |
| <td>Objects of type <code>I1</code></td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td><code>it2</code>, <code>it2t</code></td>
 | |
| <td>Objects of type <code>I2</code></td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td><code>t</code></td>
 | |
| <td>Object of type <code>T</code></td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td><code>c</code></td>
 | |
| <td>Object of type <code>C</code></td>
 | |
| </tr>
 | |
| </tbody>
 | |
| </table>
 | |
| <h4>Definitions</h4>
 | |
| <h4>Valid expressions</h4>
 | |
| <p>In addition to the expressions defined for Assignable, Equality
 | |
| Comparable and Default Constructible, the following expressions
 | |
| must be valid.</p>
 | |
| <table border="1" summary="expressions">
 | |
| <tbody>
 | |
| <tr>
 | |
| <th>Name</th>
 | |
| <th>Expression</th>
 | |
| <th>Type requirements</th>
 | |
| <th>Return type</th>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Default constructor</td>
 | |
| <td><code>I1 it</code></td>
 | |
| <td> </td>
 | |
| <td> </td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Dereference</td>
 | |
| <td><code>*it</code></td>
 | |
| <td> </td>
 | |
| <td>Convertible to <code>T</code>.</td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Dereference assignment</td>
 | |
| <td><code>*it = t</code></td>
 | |
| <td><code>I1</code> is mutable.</td>
 | |
| <td> </td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Member access</td>
 | |
| <td><code>it->m</code></td>
 | |
| <td><code>T</code> is a type for which <code>t.m</code> is
 | |
| defined.</td>
 | |
| <td> </td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Preincrement</td>
 | |
| <td><code>++ it</code></td>
 | |
| <td> </td>
 | |
| <td><code>I1 &</code></td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Postincrement</td>
 | |
| <td><code>it ++</code></td>
 | |
| <td> </td>
 | |
| <td><code>I1</code></td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Predecrement</td>
 | |
| <td><code>-- it</code></td>
 | |
| <td> </td>
 | |
| <td><code>I1 &</code></td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Postdecrement</td>
 | |
| <td><code>it --</code></td>
 | |
| <td> </td>
 | |
| <td><code>I1</code></td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Row Index</td>
 | |
| <td><code>it.index1 ()</code></td>
 | |
| <td> </td>
 | |
| <td><code>C::size_type</code></td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Column Index</td>
 | |
| <td><code>it.index2 ()</code></td>
 | |
| <td> </td>
 | |
| <td><code>C::size_type</code></td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Row/Column Begin</td>
 | |
| <td><code>it.begin ()</code></td>
 | |
| <td> </td>
 | |
| <td><code>I2</code></td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Row/Column End</td>
 | |
| <td><code>it.end ()</code></td>
 | |
| <td> </td>
 | |
| <td><code>I2</code></td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Reverse Row/Column Begin</td>
 | |
| <td><code>it.rbegin ()</code></td>
 | |
| <td> </td>
 | |
| <td><code>reverse_iterator<I2></code></td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Reverse Row/Column End</td>
 | |
| <td><code>it.rend ()</code></td>
 | |
| <td> </td>
 | |
| <td><code>reverse_iterator<I2></code></td>
 | |
| </tr>
 | |
| </tbody>
 | |
| </table>
 | |
| <h4>Expression Semantics</h4>
 | |
| <p>Semantics of an expression is defined only where it differs
 | |
| from, or is not defined in, Assignable, Equality Comparable and
 | |
| Default Constructible.</p>
 | |
| <table border="1" summary="semantics">
 | |
| <tbody>
 | |
| <tr>
 | |
| <th>Name</th>
 | |
| <th>Expression</th>
 | |
| <th>Precondition</th>
 | |
| <th>Semantics</th>
 | |
| <th>Postcondition</th>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Default constructor</td>
 | |
| <td><code>I1 it</code></td>
 | |
| <td> </td>
 | |
| <td> </td>
 | |
| <td><code>it</code> is singular.</td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Dereference</td>
 | |
| <td><code>*it</code></td>
 | |
| <td><code>it</code> is dereferenceable.</td>
 | |
| <td> </td>
 | |
| <td> </td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Dereference assignment</td>
 | |
| <td><code>*it = t</code></td>
 | |
| <td>Same as for <code>*it</code>.</td>
 | |
| <td> </td>
 | |
| <td><code>*it</code> is a copy of t.</td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Member access</td>
 | |
| <td><code>it->m</code></td>
 | |
| <td><code>it</code> is dereferenceable.</td>
 | |
| <td>Equivalent to <code>(*it).m</code></td>
 | |
| <td> </td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Preincrement</td>
 | |
| <td><code>++ it</code></td>
 | |
| <td><code>it</code> is dereferenceable.</td>
 | |
| <td><code>it</code> is modified to point to the next element of
 | |
| the column/row, i.e. for column iterators holds<br />
 | |
| <code>it.index1 () < (++ it).index1 ()</code> and<br />
 | |
| <code>it.index2 () == (++ it).index2 ()</code>,<br />
 | |
| for row iterators holds<br />
 | |
| <code>it.index1 () == (++ it).index1 ()</code> and<br />
 | |
| <code>it.index2 () < (++ it).index2 ()</code>.<br /></td>
 | |
| <td><code>it</code> is dereferenceable or past-the-end.
 | |
| <code><br />
 | |
| &it == &++ it</code>.<br />
 | |
| If <code>it1 == it2</code>,<br />
 | |
| then <code>++ it1 == ++ it2</code>.</td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Postincrement</td>
 | |
| <td><code>it ++</code></td>
 | |
| <td>Same as for <code>++ it</code>.</td>
 | |
| <td>Equivalent to<br />
 | |
| <code>{<br />
 | |
|  I1 itt = it;<br />
 | |
|  ++ it;<br />
 | |
|  return itt;<br />
 | |
| }</code></td>
 | |
| <td><code>it</code> is dereferenceable or past-the-end.</td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Predecrement</td>
 | |
| <td><code>-- it</code></td>
 | |
| <td><code>it</code> is dereferenceable or past-the-end.<br />
 | |
| There exists a dereferenceable iterator <code>itt</code> such that
 | |
| <code>it == ++ itt</code>.</td>
 | |
| <td><code>it</code> is modified to point to the previous 
 | |
| element of the column/row, i.e. for column iterators holds<br />
 | |
| <code>it.index1 () > (-- it).index1 ()</code> and<br />
 | |
| <code>it.index2 () == (-- it).index2 ()</code>,<br />
 | |
| for row iterators holds<br />
 | |
| <code>it.index1 () == (-- it).index1 ()</code> and<br />
 | |
| <code>it.index2 () > (-- it).index2 ()</code>.</td>
 | |
| <td><code>it</code> is dereferenceable.<br />
 | |
| <code>&it = &-- it</code>.<br />
 | |
| If <code>it1 == it2</code>,<br />
 | |
| then <code>-- it1 == -- it2</code>.</td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Postdecrement</td>
 | |
| <td><code>it --</code></td>
 | |
| <td>Same as for -- <code>it</code>.</td>
 | |
| <td>Equivalent to<br />
 | |
| <code>{<br />
 | |
|  I1 itt = it;<br />
 | |
|  -- it;<br />
 | |
|  return itt;<br />
 | |
| }</code></td>
 | |
| <td><code>it</code> is dereferenceable. </td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Row Index</td>
 | |
| <td><code>it.index1 ()</code></td>
 | |
| <td>If <code>it</code> is a Row iterator then <code>it</code> must be dereferenceable.</td>
 | |
| <td><code>it.index1 () >= 0</code> and<br />
 | |
| <code>it.index1 () < it () .size1 ()</code></td>
 | |
| <td>If <code>it1 == it2</code>,<br />
 | |
| then <code>it1.index1 () == 12.index1 ()</code>.<br />
 | |
| If <code>it1</code>, <code>it2</code> are Row Iterators with <code>it1 == it2</code>,<br />
 | |
| then <code>it1.index1 () < (++ it2</code>).<code>index1 ()</code>.<br />
 | |
| and <code>it1.index1 () > (-- it2</code>).<code>index1 ()</code>.</td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Column Index</td>
 | |
| <td><code>it.index2 ()</code></td>
 | |
| <td>If <code>it</code> is a Column iterator then <code>it</code> must be dereferenceable.</td>
 | |
| <td><code>it.index2 () >= 0</code> and<br />
 | |
| <code>it.index2 () < it () .size2 ()</code></td>
 | |
| <td>If <code>it1 == it2</code>,<br />
 | |
| then <code>it1.index2 () == it2</code>.<code>index2 ()</code>
 | |
| .<br />
 | |
| If <code>it1</code>, <code>it2</code> are Column Iterators with <code>it1 == i12</code>,<br />
 | |
| then <code>it1.index2 () < (++ it2</code>).<code>index2 ()</code>.<br />
 | |
| end <code>it1.index2 () > (-- it2</code>).<code>index2 ()</code>.</td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Row/Column Begin</td>
 | |
| <td><code>it.begin ()</code></td>
 | |
| <td><code>it</code> is dereferenceable.</td>
 | |
| <td>If <code>it</code> is a Column Iterator,<br />
 | |
| then <code>it2 = it.begin ()</code> is a Row Iterator<br />
 | |
| with <code>it2.index1 () == it.index1 ()</code>.
 | |
| <p>If <code>it</code> is a Row Iterator,<br />
 | |
| then <code>it2 = it.begin ()</code> is a Column Iterator<br />
 | |
| with <code>it2.index2 () == it.index2 ()</code>.</p>
 | |
| </td>
 | |
| <td> </td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Row/Column End</td>
 | |
| <td><code>it.end ()</code></td>
 | |
| <td><code>it</code> is dereferenceable.</td>
 | |
| <td>If <code>it</code> is a Column Iterator,<br />
 | |
| then <code>it2 = it.end ()</code> is a Row Iterator<br />
 | |
| with <code>it2.index1 () == it.index1 ()</code>.
 | |
| <p>If <code>it</code> is a Row Iterator,<br />
 | |
| then <code>it2 = it.end ()</code> is a Column Iterator<br />
 | |
| with <code>it2.index2 () == it.index2 ()</code>.</p>
 | |
| </td>
 | |
| <td> </td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Reverse Row/Column Begin</td>
 | |
| <td><code>it.rbegin ()</code></td>
 | |
| <td><code>it</code> is dereferenceable.</td>
 | |
| <td>Equivalent to <code>reverse_iterator<I2> (it.end
 | |
| ())</code>.</td>
 | |
| <td> </td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Reverse Row/Column End</td>
 | |
| <td><code>it.rend ()</code></td>
 | |
| <td><code>it</code> is dereferenceable.</td>
 | |
| <td>Equivalent to <code>reverse_iterator<I2> (it.begin
 | |
| ())</code>.</td>
 | |
| <td> </td>
 | |
| </tr>
 | |
| </tbody>
 | |
| </table>
 | |
| <h4>Complexity guarantees</h4>
 | |
| <p>The complexity of operations on indexed bidirectional column/row
 | |
| iterators is guaranteed to be logarithmic depending on the size of
 | |
| the container. The complexity of one iterator (depending on the
 | |
| storage layout) can be lifted to be amortized constant time. The
 | |
| complexity of the other iterator (depending on the storage layout
 | |
| and the container) can be lifted to be amortized constant time for
 | |
| the first row/first column respectively.</p>
 | |
| <h4>Invariants</h4>
 | |
| <table border="1" summary="invariants">
 | |
| <tbody>
 | |
| <tr>
 | |
| <td>Identity</td>
 | |
| <td><code>it1 == it2</code> if and only if <code>&*it1 ==
 | |
| &*it2</code>.</td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Symmetry of increment and decrement</td>
 | |
| <td>If <code>it</code> is dereferenceable, then <code>++ it;
 | |
| --it;</code> is a null operation. Similarly, <code>-- it; ++
 | |
| it;</code> is a null operation.</td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Relation between iterator index and container element
 | |
| operator</td>
 | |
| <td>If <code>it</code> is dereferenceable, <code>*it == it ()
 | |
| (it.index1 (), it.index2 ())</code></td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Relation between iterator column/row begin and iterator
 | |
| index</td>
 | |
| <td>If <code>it</code> is a Column Iterator
 | |
| and <code>it2 = it.begin ()</code> then <code>it2.index2 () <
 | |
| it2t.index2 ()</code> for all <code>it2t</code> with <code>it2t ()
 | |
| == it2 ()</code> and <code>it2t ().index1 () == it2 ().index1
 | |
| ()</code>.
 | |
| <p>If <code>it</code> is a Row Iterator and
 | |
| <code>it2 = it.begin ()</code> then <code>it2.index1 () <
 | |
| it2t.index1 ()</code> for all <code>it2t</code> with <code>it2t ()
 | |
| == it2 ()</code> and <code>it2t ().index2 () == it2 ().index2
 | |
| ()</code>.</p>
 | |
| </td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Relation between iterator column/row end and iterator
 | |
| index</td>
 | |
| <td>If <code>it</code> is a Column Iterator
 | |
| and <code>it2 = it.end ()</code> then <code>it2.index2 () >
 | |
| it2t.index2 ()</code> for all <code>it2t</code> with <code>it2t ()
 | |
| == it2 ()</code> and <code>it2t ().index1 () == it2 ().index1
 | |
| ()</code>.
 | |
| <p>If <code>it</code> is a Row Iterator and
 | |
| <code>it2 = it.end ()</code> then <code>it2.index1 () >
 | |
| it2t.index1 ()</code> for all <code>it2t</code> with <code>it2t ()
 | |
| == it2 ()</code> and <code>it2t ().index2 () == it2 ().index2
 | |
| ()</code>.</p>
 | |
| </td>
 | |
| </tr>
 | |
| </tbody>
 | |
| </table>
 | |
| <h4>Models</h4>
 | |
| <ul>
 | |
| <li><code>sparse_matrix::iterator1</code></li>
 | |
| <li><code>sparse_matrix::iterator2</code></li>
 | |
| </ul>
 | |
| <h2><a name="indexed_random_access_cr_iterator"
 | |
| ></a>Indexed Random Access Column/Row Iterator</h2>
 | |
| <h4>Description</h4>
 | |
| <p>An Indexed Random Access Column/Row Iterator is an iterator of a
 | |
| container that can be dereferenced, incremented, decremented and
 | |
| carries index information.</p>
 | |
| <h4>Refinement of</h4>
 | |
| <p><a href="#indexed_bidirectional_cr_iterator">Indexed
 | |
| Bidirectional Column/Row Iterator</a> .</p>
 | |
| <h4>Associated types</h4>
 | |
| <table border="1" summary="associated types">
 | |
| <tbody>
 | |
| <tr>
 | |
| <td>Value type</td>
 | |
| <td>The type of the value obtained by dereferencing a Indexed
 | |
| Random Access Column/Row Iterator</td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Container type</td>
 | |
| <td>The type of the container a Indexed Random Access Column/Row
 | |
| Iterator points into.</td>
 | |
| </tr>
 | |
| </tbody>
 | |
| </table>
 | |
| <h4>Notation</h4>
 | |
| <table border="0" summary="notation">
 | |
| <tbody>
 | |
| <tr>
 | |
| <td><code>I</code></td>
 | |
| <td>A type that is a model of Indexed Random Access Column/Row
 | |
| Iterator</td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td><code>T</code></td>
 | |
| <td>The value type of <code>I</code></td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td><code>C</code></td>
 | |
| <td>The container type of <code>I</code></td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td><code>it</code>, <code>itt, it1</code>, <code>it2</code></td>
 | |
| <td>Objects of type <code>I</code></td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td><code>t</code></td>
 | |
| <td>Object of type <code>T</code></td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td><code>c</code></td>
 | |
| <td>Object of type <code>C</code></td>
 | |
| </tr>
 | |
| </tbody>
 | |
| </table>
 | |
| <h4>Definitions</h4>
 | |
| <h4>Valid expressions</h4>
 | |
| <p>In addition to the expressions defined for <a href=
 | |
| "#indexed_bidirectional_cr_iterator">Indexed Bidirectional
 | |
| Column/Row Iterator</a> , the following expressions must be
 | |
| valid.</p>
 | |
| <table border="1" summary="expressions">
 | |
| <tbody>
 | |
| <tr>
 | |
| <th>Name</th>
 | |
| <th>Expression</th>
 | |
| <th>Type requirements</th>
 | |
| <th>Return type</th>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Forward motion</td>
 | |
| <td><code>it += n</code></td>
 | |
| <td> </td>
 | |
| <td><code>I &</code></td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Iterator addition</td>
 | |
| <td><code>it + n</code></td>
 | |
| <td> </td>
 | |
| <td><code>I</code></td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Backward motion</td>
 | |
| <td><code>i -= n</code></td>
 | |
| <td> </td>
 | |
| <td><code>I &</code></td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Iterator subtraction</td>
 | |
| <td><code>it - n</code></td>
 | |
| <td> </td>
 | |
| <td><code>I</code> </td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Difference</td>
 | |
| <td><code>it1 - it2</code></td>
 | |
| <td> </td>
 | |
| <td><code>C::difference_type</code></td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Element operator</td>
 | |
| <td><code>it [n]</code></td>
 | |
| <td> </td>
 | |
| <td>Convertible to <code>T</code>.</td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Element assignment</td>
 | |
| <td><code>it [n] = t</code></td>
 | |
| <td><code>I</code> is mutable</td>
 | |
| <td>Convertible to <code>T</code>.</td>
 | |
| </tr>
 | |
| </tbody>
 | |
| </table>
 | |
| <h4>Expression Semantics</h4>
 | |
| <p>Semantics of an expression is defined only where it differs
 | |
| from, or is not defined in, <a href=
 | |
| "#indexed_bidirectional_cr_iterator">Indexed Bidirectional
 | |
| Column/Row Iterator</a> .</p>
 | |
| <table border="1" summary="semantics">
 | |
| <tbody>
 | |
| <tr>
 | |
| <th>Name</th>
 | |
| <th>Expression</th>
 | |
| <th>Precondition</th>
 | |
| <th>Semantics</th>
 | |
| <th>Postcondition</th>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Forward motion</td>
 | |
| <td><code>it += n</code></td>
 | |
| <td>Including <code>it</code> itself, there must be <code>n</code>
 | |
| dereferenceable or past-the-end iterators following or preceding
 | |
| <code>it</code>, depending on whether <code>n</code> is positive or
 | |
| negative.</td>
 | |
| <td>If <code>n > 0</code>, equivalent to executing <code>++
 | |
| it</code> <code>n</code> times. If <code>n < 0</code>,
 | |
| equivalent to executing <code>-- it</code> <code>n</code> times. If
 | |
| <code>n == 0</code>, this is a null operation.</td>
 | |
| <td><code>it</code> is dereferenceable or past-the-end.</td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Iterator addition</td>
 | |
| <td><code>it + n</code></td>
 | |
| <td>Same as for <code>i += n</code>.</td>
 | |
| <td>Equivalent to<br />
 | |
| <code>{<br />
 | |
|  I itt = it;<br />
 | |
|  return itt += n;<br />
 | |
| }</code></td>
 | |
| <td>Result is dereferenceable or past-the-end.</td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Backward motion</td>
 | |
| <td><code>it -= n</code></td>
 | |
| <td>Including <code>it</code> itself, there must be <code>n</code>
 | |
| dereferenceable or past-the-end iterators preceding or following
 | |
| <code>it</code>, depending on whether <code>n</code> is positive or
 | |
| negative.</td>
 | |
| <td>Equivalent to <code>it += (-n)</code>.</td>
 | |
| <td><code>it</code> is dereferenceable or past-the-end.</td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Iterator subtraction</td>
 | |
| <td><code>it - n</code></td>
 | |
| <td>Same as for <code>i -= n</code>.</td>
 | |
| <td>Equivalent to<br />
 | |
| <code>{<br />
 | |
|  I itt = it;<br />
 | |
|  return itt -= n;<br />
 | |
| }</code></td>
 | |
| <td>Result is dereferenceable or past-the-end.</td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Difference</td>
 | |
| <td><code>it1 - it2</code></td>
 | |
| <td>Either <code>it1</code> is reachable from <code>it2</code> or
 | |
| <code>it2</code> is reachable from <code>it1</code>, or both.</td>
 | |
| <td>Returns a number <code>n</code> such that <code>it1 == it2 +
 | |
| n</code></td>
 | |
| <td> </td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Element operator</td>
 | |
| <td><code>it [n]</code></td>
 | |
| <td><code>it + n</code> exists and is dereferenceable.</td>
 | |
| <td>Equivalent to <code>*(it + n)</code></td>
 | |
| <td> </td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Element assignment</td>
 | |
| <td><code>i[n] = t</code></td>
 | |
| <td>Same as for <code>it [n]</code>.</td>
 | |
| <td>Equivalent to <code>*(it + n) = t</code></td>
 | |
| <td> </td>
 | |
| </tr>
 | |
| </tbody>
 | |
| </table>
 | |
| <h4>Complexity guarantees</h4>
 | |
| <p>The complexity of operations on indexed random access Column/Row
 | |
| iterators is guaranteed to be amortized constant time.</p>
 | |
| <h4>Invariants</h4>
 | |
| <table border="1" summary="invariants">
 | |
| <tbody>
 | |
| <tr>
 | |
| <td>Symmetry of addition and subtraction</td>
 | |
| <td>If <code>it + n</code> is well-defined, then <code>it += n; it
 | |
| -= n;</code> and <code>(it + n) - n</code> are null operations.
 | |
| Similarly, if <code>it - n</code> is well-defined, then <code>it -=
 | |
| n; it += n;</code> and <code>(it - n) + n</code> are null
 | |
| operations.</td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Relation between distance and addition</td>
 | |
| <td>If <code>it1 - it2</code> is well-defined, then <code>it1 ==
 | |
| it2 + (it1 - it2)</code>.</td>
 | |
| </tr>
 | |
| <tr>
 | |
| <td>Reachability and distance</td>
 | |
| <td>If <code>it1</code> is reachable from <code>it2</code>, then
 | |
| <code>it1 - it2 >= 0</code>.</td>
 | |
| </tr>
 | |
| </tbody>
 | |
| </table>
 | |
| <h4>Models</h4>
 | |
| <ul>
 | |
| <li><code>matrix::iterator1</code></li>
 | |
| <li><code>matrix::iterator2</code></li>
 | |
| </ul>
 | |
| <hr />
 | |
| <p>Copyright (©) 2000-2002 Joerg Walter, Mathias Koch<br />
 | |
|    Use, modification and distribution are subject to the
 | |
|    Boost Software License, Version 1.0.
 | |
|    (See accompanying file LICENSE_1_0.txt
 | |
|    or copy at <a href="http://www.boost.org/LICENSE_1_0.txt">
 | |
|       http://www.boost.org/LICENSE_1_0.txt
 | |
|    </a>).
 | |
| </p>
 | |
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