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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"><!-- /home/reggie/tmp/qt-3.0-reggie-5401/qt-x11-commercial-3.0.5/doc/qmap.doc:559 --><html><head><meta http-equiv="Content-Type" content="text/html; charset=ISO-8859-1"><title>QMapIterator Class</title><style type="text/css"><!--h3.fn,span.fn { margin-left: 1cm; text-indent: -1cm; }a:link { color: #004faf; text-decoration: none }a:visited { color: #672967; text-decoration: none }body { background: #ffffff; color: black; }--></style></head><body><table border="0" cellpadding="0" cellspacing="0" width="100%"><tr bgcolor="#E5E5E5"><td valign=center> <a href="index.html"><font color="#004faf">Home</font></a> | <a href="classes.html"><font color="#004faf">All Classes</font></a> | <a href="mainclasses.html"><font color="#004faf">Main Classes</font></a> | <a href="annotated.html"><font color="#004faf">Annotated</font></a> | <a href="groups.html"><font color="#004faf">Grouped Classes</font></a> | <a href="functions.html"><font color="#004faf">Functions</font></a></td><td align="right" valign="center"><img src="logo32.png" align="right" width="64" height="32" border="0"></td></tr></table><h1 align=center>QMapIterator Class Reference</h1><p>The QMapIterator class provides an iterator for QMap.<a href="#details">More...</a><p><tt>#include <<a href="qmap-h.html">qmap.h</a>></tt><p><a href="qmapiterator-members.html">List of all member functions.</a><h2>Public Members</h2><ul><li><div class=fn>typedef std::bidirectional_iterator_tag <a href="#iterator_category"><b>iterator_category</b></a></div></li><li><div class=fn>typedef T <a href="#value_type"><b>value_type</b></a></div></li><li><div class=fn>typedef T * <a href="#pointer"><b>pointer</b></a></div></li><li><div class=fn>typedef T & <a href="#reference"><b>reference</b></a></div></li><li><div class=fn><a href="#QMapIterator"><b>QMapIterator</b></a> ()</div></li><li><div class=fn><a href="#QMapIterator-2"><b>QMapIterator</b></a> ( QMapNode<K, T> * p )</div></li><li><div class=fn><a href="#QMapIterator-3"><b>QMapIterator</b></a> ( const QMapIterator<K, T> & it )</div></li><li><div class=fn>bool <a href="#operator-eq-eq"><b>operator==</b></a> ( const QMapIterator<K, T> & it ) const</div></li><li><div class=fn>bool <a href="#operator!-eq"><b>operator!=</b></a> ( const QMapIterator<K, T> & it ) const</div></li><li><div class=fn>T & <a href="#operator*"><b>operator*</b></a> ()</div></li><li><div class=fn>const T & <a href="#operator*-2"><b>operator*</b></a> () const</div></li><li><div class=fn>const K & <a href="#key"><b>key</b></a> () const</div></li><li><div class=fn>T & <a href="#data"><b>data</b></a> ()</div></li><li><div class=fn>const T & <a href="#data-2"><b>data</b></a> () const</div></li><li><div class=fn>QMapIterator<K, T> & <a href="#operator++"><b>operator++</b></a> ()</div></li><li><div class=fn>QMapIterator<K, T> <a href="#operator++-2"><b>operator++</b></a> ( int )</div></li><li><div class=fn>QMapIterator<K, T> & <a href="#operator--"><b>operator--</b></a> ()</div></li><li><div class=fn>QMapIterator<K, T> <a href="#operator---2"><b>operator--</b></a> ( int )</div></li></ul><hr><a name="details"></a><h2>Detailed Description</h2>The QMapIterator class provides an iterator for <a href="qmap.html">QMap</a>.<p> <p> You cannot create an iterator by yourself. Instead, you have to aska map to give you one. An iterator is as big as a pointer;on 32-bit machines that means 4 bytes, on 64-bit ones 8 bytes. That makescopying them very fast. They resemble the semantics of pointers asmuch as possible, and they are almost as fast as usual pointers.See the <a href="qmap.html#qmap-eg">QMap example</a>.<p> The only way to traverse a map is to use iterators. QMap is highlyoptimized for performance and memory usage. On the other hand thismeans that you have to be a bit more careful with what you aredoing. QMap does not know about all its iterators, and the iteratorsdon't even know to which map they belong. That makes things fast buta bit dangerous because it is up to you to make sure that theiterators you are using are still valid. <a href="qdictiterator.html">QDictIterator</a> will be ableto give warnings, whereas QMapIterator may end up in an undefinedstate.<p> For every Iterator there is also a ConstIterator. You have to usethe ConstIterator to access a <a href="qmap.html">QMap</a> in a const environment or if thereference or pointer to the map is itself const. Its semantics arethe same, but it returns only const references to the item it pointsto.<p> <p>See also <a href="qmap.html">QMap</a>, <a href="qmapconstiterator.html">QMapConstIterator</a>, <a href="qtl.html">Qt Template Library Classes</a> and <a href="tools.html">Non-GUI Classes</a>.<hr><h2>Member Type Documentation</h2><h3 class=fn><a name="iterator_category"></a>QMapIterator::iterator_category</h3> The type of iterator category, <tt>std::bidirectional_iterator_tag</tt>. <h3 class=fn><a name="pointer"></a>QMapIterator::pointer</h3> Pointer to value_type. <h3 class=fn><a name="reference"></a>QMapIterator::reference</h3> Reference to value_type. <h3 class=fn><a name="value_type"></a>QMapIterator::value_type</h3> The type of value. <hr><h2>Member Function Documentation</h2><h3 class=fn><a name="QMapIterator"></a>QMapIterator::QMapIterator ()</h3>Creates an uninitialized iterator.<h3 class=fn><a name="QMapIterator-2"></a>QMapIterator::QMapIterator ( QMapNode<K, T> * p )</h3>Constructs an iterator starting at node <em>p</em>.<h3 class=fn><a name="QMapIterator-3"></a>QMapIterator::QMapIterator ( const <a href="qmapiterator.html">QMapIterator</a><K, T> & it )</h3>Constructs a copy of the iterator, <em>it</em>.<h3 class=fn>T & <a name="data"></a>QMapIterator::data ()</h3><p> Returns a reference to the current item.<h3 class=fn>const T & <a name="data-2"></a>QMapIterator::data () const</h3><p> This is an overloaded member function, provided for convenience. It behaves essentially like the above function.<p> Returns a const reference to the data of the current item.<h3 class=fn>const K & <a name="key"></a>QMapIterator::key () const</h3><p> Returns a const reference to the data of the current key.<h3 class=fn>bool <a name="operator!-eq"></a>QMapIterator::operator!= ( const <a href="qmapiterator.html">QMapIterator</a><K, T> & it ) const</h3><p> Compares the iterator to the <em>it</em> iterator and returns FALSE if theypoint to the same item; otherwise returns TRUE.<h3 class=fn>T & <a name="operator*"></a>QMapIterator::operator* ()</h3><p> Dereference operator. Returns a reference to the current item. The sameas <a href="#data">data</a>().<h3 class=fn>const T & <a name="operator*-2"></a>QMapIterator::operator* () const</h3><p> This is an overloaded member function, provided for convenience. It behaves essentially like the above function.<p> Dereference operator. Returns a const reference to the current item. Thesame as <a href="#data">data</a>().<h3 class=fn><a href="qmapiterator.html">QMapIterator</a><K, T> & <a name="operator++"></a>QMapIterator::operator++ ()</h3><p> Prefix ++ makes the succeeding item current and returns an iteratorpointing to the new current item. The iterator cannot checkwhether it reached the end of the map. Incrementing the iterator returned by end() causes undefined results.<h3 class=fn><a href="qmapiterator.html">QMapIterator</a><K, T> <a name="operator++-2"></a>QMapIterator::operator++ ( int )</h3><p> This is an overloaded member function, provided for convenience. It behaves essentially like the above function.<p> Postfix ++ makes the succeeding item current and returns an iteratorpointing to the new current item. The iterator cannot checkwhether it reached the end of the map. Incrementing the iterator returned by end() causes undefined results.<h3 class=fn><a href="qmapiterator.html">QMapIterator</a><K, T> & <a name="operator--"></a>QMapIterator::operator-- ()</h3><p> Prefix -- makes the previous item current and returns an iteratorpointing to the new current item. The iterator cannot checkwhether it reached the beginning of the map. Decrementing theiterator returned by begin() causes undefined results.<h3 class=fn><a href="qmapiterator.html">QMapIterator</a><K, T> <a name="operator---2"></a>QMapIterator::operator-- ( int )</h3><p> This is an overloaded member function, provided for convenience. It behaves essentially like the above function.<p> Postfix -- makes the previous item current and returns an iteratorpointing to the new current item. The iterator cannot checkwhether it reached the beginning of the map. Decrementing theiterator returned by begin() causes undefined results.<h3 class=fn>bool <a name="operator-eq-eq"></a>QMapIterator::operator== ( const <a href="qmapiterator.html">QMapIterator</a><K, T> & it ) const</h3><p> Compares the iterator to the <em>it</em> iterator and returns TRUE if theypoint to the same item; otherwise returns FALSE.<!-- eof --><hr><p>This file is part of the <a href="index.html">Qt toolkit</a>.Copyright © 1995-2002<a href="http://www.trolltech.com/">Trolltech</a>. All Rights Reserved.<p><address><hr><div align=center><table width=100% cellspacing=0 border=0><tr><td>Copyright © 2002 <a href="http://www.trolltech.com">Trolltech</a><td><a href="http://www.trolltech.com/trademarks.html">Trademarks</a><td align=right><div align=right>Qt version 3.0.5</div></table></div></address></body></html>⌨️ 快捷键说明
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