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- BoostBook element rationale"><link rel="refentry" href="Assignable.html" title="Concept Assignable"><link rel="refentry" href="InputIterator.html" title="Concept InputIterator"><link rel="refentry" href="OutputIterator.html" title="Concept OutputIterator"><link rel="refentry" href="ForwardIterator.html" title="Concept ForwardIterator"><link rel="refentry" href="BidirectionalIterator.html" title="Concept BidirectionalIterator"><link rel="refentry" href="RandomAccessIterator.html" title="Concept RandomAccessIterator"><link rel="refentry" href="DefaultConstructible.html" title="Concept DefaultConstructible"><link rel="refentry" href="CopyConstructible.html" title="Concept CopyConstructible"><link rel="refentry" href="EqualityComparable.html" title="Concept EqualityComparable"><link rel="refentry" href="LessThanComparable.html" title="Concept LessThanComparable"><link rel="refentry" href="SignedInteger.html" title="Concept SignedInteger"><link rel="section" href="ForwardIterator.html#id2552426" title="Description"><link rel="section" href="ForwardIterator.html#id2552441" title="Refinement of"><link rel="section" href="ForwardIterator.html#id2552462" title="Associated types"><link rel="section" href="ForwardIterator.html#id2552503" title="Notation"><link rel="section" href="ForwardIterator.html#id2552541" title="Type expressions"><link rel="section" href="ForwardIterator.html#id2552559" title="Valid expressions"><link rel="section" href="ForwardIterator.html#id2552691" title="Complexity"><link rel="section" href="ForwardIterator.html#id2552698" title="Invariants"><link rel="section" href="ForwardIterator.html#id2552729" title="Models"><link rel="section" href="ForwardIterator.html#id2552750" title="See also"></head><body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"><table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" border="1" cellpadding="2" bgcolor="#007F7F"><tr><td bgcolor="#FFFFFF"><img src="../../c++boost.gif" alt="c++boost.gif (8819 bytes)" width="277" height="86"></td><td><a href="../../index.htm"><font color="#FFFFFF" size="4" face="Arial">Home</font></a></td><td><a href="libraries.html"><font color="#FFFFFF" size="4" face="Arial">Libraries</font></a></td><td><a href="../../people/people.htm"><font color="#FFFFFF" size="4" face="Arial">People</font></a></td><td><a href="../../more/faq.htm"><font color="#FFFFFF" size="4" face="Arial">FAQ</font></a></td><td><a href="../../more/index.htm"><font color="#FFFFFF" size="4" face="Arial">More</font></a></td></tr></table><div class="refentry" lang="en"><a name="ForwardIterator"></a><div class="titlepage"><div></div><div></div></div><div class="refnamediv"><h2><span class="refentrytitle">Concept ForwardIterator</span></h2><p>ForwardIterator</p></div><div class="refsect1" lang="en"><h2>Description</h2><p>A forward iterator is an iterator that can read through a sequence of
- values. It is multi-pass (old values of the iterator can be
- re-used), and can be either mutable (data pointed to by it can be
- changed) or not mutable.</p><p>An 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).</p></div><div class="refsect1" lang="en"><h2>Refinement of</h2><div class="itemizedlist"><ul type="disc"><li><p><a href="InputIterator.html" title="Concept InputIterator">InputIterator</a></p></li><li><p><a href="OutputIterator.html" title="Concept OutputIterator">OutputIterator</a></p></li></ul></div></div><div class="refsect1" lang="en"><h2>Associated types</h2><div class="itemizedlist"><ul type="disc"><li><p><span class="bold"><b>value_type</b></span></p><pre class="literallayout">std::iterator_traits<Iter>::value_type</pre><p>The value type of the iterator</p></li><li><p><span class="bold"><b>category</b></span></p><pre class="literallayout">std::iterator_traits<Iter>::iterator_category</pre><p>The category of the iterator</p></li></ul></div></div><div class="refsect1" lang="en"><h2>Notation</h2><div class="variablelist"><dl><dt><span class="term">Iter</span></dt><dd>A type playing the role of iterator-type in the <a href="ForwardIterator.html" title="Concept ForwardIterator">ForwardIterator</a> concept.</dd><dt><span class="term"><tt class="varname">i</tt>, </span><span class="term"><tt class="varname">j</tt></span></dt><dd>Objects of type Iter</dd><dt><span class="term"><tt class="varname">x</tt></span></dt><dd>Object of type value_type</dd></dl></div></div><div class="refsect1" lang="en"><h2>Type expressions</h2><div class="variablelist"><dl><dt><span class="term">Category tag</span></dt><dd><p><span class="type">category</span> must be
- derived from <span class="type">std::forward_iterator_tag</span>.
- </p></dd></dl></div></div><div class="refsect1" lang="en"><h2>Valid expressions</h2><div class="informaltable"><table border="1"><colgroup><col><col><col><col><col><col></colgroup><thead><tr><th>Name</th><th>Expression</th><th>Type</th><th>Precondition</th><th>Semantics</th><th>Postcondition</th></tr></thead><tbody><tr><td><p>Dereference</p></td><td><p>*i</p></td><td><p><span class="type">const-if-not-mutable value_type &</span></p></td><td><p><tt class="computeroutput">i</tt> is incrementable (not
- off-the-end)</p></td><td> </td><td> </td></tr><tr><td><p>Member access</p></td><td><p>i->{member-name} (return type is pointer-to-object type)</p></td><td><p><span class="type">const-if-not-mutable value_type *</span></p></td><td><p><tt class="computeroutput">i</tt> is incrementable (not
- off-the-end)</p></td><td> </td><td> </td></tr><tr><td><p>Preincrement</p></td><td><p>++i</p></td><td><p><span class="type">Iter &</span></p></td><td><p><tt class="computeroutput">i</tt> is incrementable (not
- off-the-end)</p></td><td> </td><td> </td></tr><tr><td><p>Postincrement</p></td><td><p>i++</p></td><td><p><span class="type">Iter</span></p></td><td><p><tt class="computeroutput">i</tt> is incrementable (not
- off-the-end)</p></td><td><p>Equivalent to <tt class="computeroutput">{Iter j = i; ++i; return j;}</tt></p></td><td><p><tt class="computeroutput">i</tt> is dereferenceable or
- off-the-end</p></td></tr></tbody></table></div></div><div class="refsect1" lang="en"><h2>Complexity</h2><p>
- All iterator operations must take amortized constant time.
- </p></div><div class="refsect1" lang="en"><h2>Invariants</h2><div class="variablelist"><dl><dt><span class="term">Predecrement must return object</span></dt><dd><p><tt class="computeroutput">&i = &(++i)</tt></p></dd><dt><span class="term">Unique path through sequence</span></dt><dd><p><tt class="computeroutput">i == j</tt> implies <tt class="computeroutput">++i == ++j</tt></p></dd></dl></div></div><div class="refsect1" lang="en"><h2>Models</h2><div class="itemizedlist"><ul type="disc"><li><span class="simplelist"><span class="type">T *</span></span></li><li><span class="simplelist"><span class="type">std::hash_set<T>::iterator</span></span></li></ul></div></div><div class="refsect1" lang="en"><h2>See also</h2><div class="itemizedlist"><ul type="disc"><li><p><a href="BidirectionalIterator.html" title="Concept BidirectionalIterator">BidirectionalIterator</a></p></li></ul></div></div></div><table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr><td align="left"><small>Last revised: , at GMT</small></td><td align="right"><small>Copyright © 2001, 2002 Indiana University<br>Copyright © 2000, 2001 University of Notre Dame du Lac<br>Copyright © 2000 Jeremy Siek, Lie-Quan Lee, Andrew Lumsdaine<br>Copyright © 1996-1999 Silicon Graphics Computer Systems, Inc.<br>Copyright © 1994 Hewlett-Packard Company</small></td></tr></table><div class="navfooter"><hr><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="OutputIterator.html"><img src="images/prev.png" alt="Prev"></a> </td><td width="20%" align="center"><a accesskey="u" href="index.html#concepts.reference"><img src="images/up.png" alt="Up"></a></td><td width="40%" align="right"> <a accesskey="n" href="BidirectionalIterator.html"><img src="images/next.png" alt="Next"></a></td></tr><tr><td width="40%" align="left" valign="top">Concept OutputIterator </td><td width="20%" align="center"><a accesskey="h" href="index.html"><img src="images/home.png" alt="Home"></a></td><td width="40%" align="right" valign="top"> Concept BidirectionalIterator</td></tr></table></div></body></html>
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