<?xml version="1.0" encoding="UTF-8"?> <!DOCTYPE html> <html lang="en"> <head> <meta http-equiv="Content-Type" content="text/html; charset=utf-8" /> <!-- qqueue.cpp --> <title>QQueue Class | Qt Core 5.9</title> <link rel="stylesheet" type="text/css" href="style/offline-simple.css" /> <script type="text/javascript"> document.getElementsByTagName("link").item(0).setAttribute("href", "style/offline.css"); // loading style sheet breaks anchors that were jumped to before // so force jumping to anchor again setTimeout(function() { var anchor = location.hash; // need to jump to different anchor first (e.g. none) location.hash = "#"; setTimeout(function() { location.hash = anchor; }, 0); }, 0); </script> </head> <body> <div class="header" id="qtdocheader"> <div class="main"> <div class="main-rounded"> <div class="navigationbar"> <table><tr> <td >Qt 5.9</td><td ><a href="qtcore-index.html">Qt Core</a></td><td ><a href="qtcore-module.html">C++ Classes</a></td><td >QQueue</td></tr></table><table class="buildversion"><tr> <td id="buildversion" width="100%" align="right">Qt 5.9.4 Reference Documentation</td> </tr></table> </div> </div> <div class="content"> <div class="line"> <div class="content mainContent"> <div class="sidebar"> <div class="toc"> <h3><a name="toc">Contents</a></h3> <ul> <li class="level1"><a href="#public-functions">Public Functions</a></li> <li class="level1"><a href="#details">Detailed Description</a></li> </ul> </div> <div class="sidebar-content" id="sidebar-content"></div></div> <h1 class="title">QQueue Class</h1> <!-- $$$QQueue-brief --> <p>The <a href="qqueue.html">QQueue</a> class is a generic container that provides a queue. <a href="#details">More...</a></p> <!-- @@@QQueue --> <div class="table"><table class="alignedsummary"> <tr><td class="memItemLeft rightAlign topAlign"> Header:</td><td class="memItemRight bottomAlign"> <span class="preprocessor">#include <QQueue></span> </td></tr><tr><td class="memItemLeft rightAlign topAlign"> qmake:</td><td class="memItemRight bottomAlign"> QT += core</td></tr><tr><td class="memItemLeft rightAlign topAlign"> Inherits:</td><td class="memItemRight bottomAlign"> <a href="qlist.html">QList</a></td></tr></table></div><ul> <li><a href="qqueue-members.html">List of all members, including inherited members</a></li> </ul> <p><b>Note:</b> All functions in this class are reentrant.</p> <a name="public-functions"></a> <h2 id="public-functions">Public Functions</h2> <div class="table"><table class="alignedsummary"> <tr><td class="memItemLeft rightAlign topAlign"> T </td><td class="memItemRight bottomAlign"><b><a href="qqueue.html#dequeue">dequeue</a></b>()</td></tr> <tr><td class="memItemLeft rightAlign topAlign"> void </td><td class="memItemRight bottomAlign"><b><a href="qqueue.html#enqueue">enqueue</a></b>(const T &<i>t</i>)</td></tr> <tr><td class="memItemLeft rightAlign topAlign"> T &</td><td class="memItemRight bottomAlign"><b><a href="qqueue.html#head">head</a></b>()</td></tr> <tr><td class="memItemLeft rightAlign topAlign"> const T &</td><td class="memItemRight bottomAlign"><b><a href="qqueue.html#head-1">head</a></b>() const</td></tr> <tr><td class="memItemLeft rightAlign topAlign"> void </td><td class="memItemRight bottomAlign"><b><a href="qqueue.html#swap">swap</a></b>(QQueue<T> &<i>other</i>)</td></tr> </table></div> <ul> <li class="fn">78 public functions inherited from <a href="qlist.html#public-functions">QList</a></li> </ul> <h3>Additional Inherited Members</h3> <ul> <li class="fn">3 static public members inherited from <a href="qlist.html#static-public-members">QList</a></li> </ul> <a name="details"></a> <!-- $$$QQueue-description --> <div class="descr"> <h2 id="details">Detailed Description</h2> <p>The <a href="qqueue.html">QQueue</a> class is a generic container that provides a queue.</p> <p><a href="qqueue.html">QQueue</a><T> is one of Qt's generic <a href="containers.html">container classes</a>. It implements a queue data structure for items of a same type.</p> <p>A queue is a first in, first out (FIFO) structure. Items are added to the tail of the queue using <a href="qqueue.html#enqueue">enqueue</a>() and retrieved from the head using <a href="qqueue.html#dequeue">dequeue</a>(). The <a href="qqueue.html#head">head</a>() function provides access to the head item without removing it.</p> <p>Example:</p> <pre class="cpp"> <span class="type"><a href="qqueue.html">QQueue</a></span><span class="operator"><</span><span class="type">int</span><span class="operator">></span> queue; queue<span class="operator">.</span>enqueue(<span class="number">1</span>); queue<span class="operator">.</span>enqueue(<span class="number">2</span>); queue<span class="operator">.</span>enqueue(<span class="number">3</span>); <span class="keyword">while</span> (<span class="operator">!</span>queue<span class="operator">.</span>isEmpty()) cout <span class="operator"><</span><span class="operator"><</span> queue<span class="operator">.</span>dequeue() <span class="operator"><</span><span class="operator"><</span> endl; </pre> <p>The example will output 1, 2, 3 in that order.</p> <p><a href="qqueue.html">QQueue</a> inherits from <a href="qlist.html">QList</a>. All of <a href="qlist.html">QList</a>'s functionality also applies to <a href="qqueue.html">QQueue</a>. For example, you can use <a href="qlist.html#isEmpty">isEmpty</a>() to test whether the queue is empty, and you can traverse a <a href="qqueue.html">QQueue</a> using <a href="qlist.html">QList</a>'s iterator classes (for example, <a href="qlistiterator.html">QListIterator</a>). But in addition, <a href="qqueue.html">QQueue</a> provides three convenience functions that make it easy to implement FIFO semantics: <a href="qqueue.html#enqueue">enqueue</a>(), <a href="qqueue.html#dequeue">dequeue</a>(), and <a href="qqueue.html#head">head</a>().</p> <p><a href="qqueue.html">QQueue</a>'s value type must be an <a href="containers.html#assignable-data-type">assignable data type</a>. This covers most data types that are commonly used, but the compiler won't let you, for example, store a <a href="../qtwidgets/qwidget.html">QWidget</a> as a value. Use <a href="../qtwidgets/qwidget.html">QWidget</a>* instead.</p> </div> <p><b>See also </b><a href="qlist.html">QList</a> and <a href="qstack.html">QStack</a>.</p> <!-- @@@QQueue --> <div class="func"> <h2>Member Function Documentation</h2> <!-- $$$dequeue[overload1]$$$dequeue --> <h3 class="fn" id="dequeue"><a name="dequeue"></a><span class="type">T</span> QQueue::<span class="name">dequeue</span>()</h3> <p>Removes the head item in the queue and returns it. This function assumes that the queue isn't empty.</p> <p>This is the same as <a href="qlist.html#takeFirst">QList::takeFirst</a>().</p> <p><b>See also </b><a href="qqueue.html#head">head</a>(), <a href="qqueue.html#enqueue">enqueue</a>(), and <a href="qlist.html#isEmpty">isEmpty</a>().</p> <!-- @@@dequeue --> <!-- $$$enqueue[overload1]$$$enqueueconstT& --> <h3 class="fn" id="enqueue"><a name="enqueue"></a><span class="type">void</span> QQueue::<span class="name">enqueue</span>(const <span class="type">T</span> &<i>t</i>)</h3> <p>Adds value <i>t</i> to the tail of the queue.</p> <p>This is the same as <a href="qlist.html#append">QList::append</a>().</p> <p><b>See also </b><a href="qqueue.html#dequeue">dequeue</a>() and <a href="qqueue.html#head">head</a>().</p> <!-- @@@enqueue --> <!-- $$$head[overload1]$$$head --> <h3 class="fn" id="head"><a name="head"></a><span class="type">T</span> &QQueue::<span class="name">head</span>()</h3> <p>Returns a reference to the queue's head item. This function assumes that the queue isn't empty.</p> <p>This is the same as <a href="qlist.html#first">QList::first</a>().</p> <p><b>See also </b><a href="qqueue.html#dequeue">dequeue</a>(), <a href="qqueue.html#enqueue">enqueue</a>(), and <a href="qlist.html#isEmpty">isEmpty</a>().</p> <!-- @@@head --> <!-- $$$head$$$head --> <h3 class="fn" id="head-1"><a name="head-1"></a>const <span class="type">T</span> &QQueue::<span class="name">head</span>() const</h3> <p>This is an overloaded function.</p> <!-- @@@head --> <!-- $$$swap[overload1]$$$swapQQueue<T>& --> <h3 class="fn" id="swap"><a name="swap"></a><span class="type">void</span> QQueue::<span class="name">swap</span>(<span class="type"><a href="qqueue.html">QQueue</a></span><<span class="type">T</span>> &<i>other</i>)</h3> <p>Swaps queue <i>other</i> with this queue. This operation is very fast and never fails.</p> <p>This function was introduced in Qt 4.8.</p> <!-- @@@swap --> </div> </div> </div> </div> </div> </div> <div class="footer"> <p> <acronym title="Copyright">©</acronym> 2017 The Qt Company Ltd. Documentation contributions included herein are the copyrights of their respective owners.<br> The documentation provided herein is licensed under the terms of the <a href="http://www.gnu.org/licenses/fdl.html">GNU Free Documentation License version 1.3</a> as published by the Free Software Foundation.<br> Qt and respective logos are trademarks of The Qt Company Ltd. in Finland and/or other countries worldwide. All other trademarks are property of their respective owners. </p> </div> </body> </html>