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<a href="index.html" class="qtref"><span>Qt Reference Documentation</span></a>
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<h3><a name="toc">Contents</a></h3>
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<li class="level1"><a href="#public-functions">Public Functions</a></li>
<li class="level1"><a href="#details">Detailed Description</a></li>
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<h1 class="title">const_iterator Class Reference</h1>
<span class="small-subtitle">(QLinkedList::const_iterator)<br/></span>
<!-- $$$const_iterator-brief -->
<p>The QLinkedList::const_iterator class provides an STL-style const iterator for <a href="qlinkedlist.html">QLinkedList</a>. <a href="#details">More...</a></p>
<!-- @@@const_iterator -->
<pre class="cpp"> <span class="preprocessor">#include <<a href="qlinkedlist.html">QLinkedList</a>></span></pre><p><b>Inherited by: </b><a href="q3valuelistconstiterator.html" class="compat">Q3ValueListConstIterator</a>.</p>
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<li><a href="qlinkedlist-const-iterator-members.html">List of all members, including inherited members</a></li>
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<a name="public-functions"></a>
<h2>Public Functions</h2>
<table class="alignedsummary">
<tr><td class="memItemLeft rightAlign topAlign"> </td><td class="memItemRight bottomAlign"><b><a href="qlinkedlist-const-iterator.html#const_iterator">const_iterator</a></b> ()</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> </td><td class="memItemRight bottomAlign"><b><a href="qlinkedlist-const-iterator.html#const_iterator-3">const_iterator</a></b> ( const const_iterator & <i>other</i> )</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> </td><td class="memItemRight bottomAlign"><b><a href="qlinkedlist-const-iterator.html#const_iterator-4">const_iterator</a></b> ( iterator <i>other</i> )</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> bool </td><td class="memItemRight bottomAlign"><b><a href="qlinkedlist-const-iterator.html#operator-not-eq">operator!=</a></b> ( const const_iterator & <i>other</i> ) const</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> const T & </td><td class="memItemRight bottomAlign"><b><a href="qlinkedlist-const-iterator.html#operator-2a">operator*</a></b> () const</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> const_iterator </td><td class="memItemRight bottomAlign"><b><a href="qlinkedlist-const-iterator.html#operator-2b">operator+</a></b> ( int <i>j</i> ) const</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> const_iterator & </td><td class="memItemRight bottomAlign"><b><a href="qlinkedlist-const-iterator.html#operator-2b-2b">operator++</a></b> ()</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> const_iterator </td><td class="memItemRight bottomAlign"><b><a href="qlinkedlist-const-iterator.html#operator-2b-2b-2">operator++</a></b> ( int )</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> const_iterator & </td><td class="memItemRight bottomAlign"><b><a href="qlinkedlist-const-iterator.html#operator-2b-eq">operator+=</a></b> ( int <i>j</i> )</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> const_iterator </td><td class="memItemRight bottomAlign"><b><a href="qlinkedlist-const-iterator.html#operator-">operator-</a></b> ( int <i>j</i> ) const</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> const_iterator & </td><td class="memItemRight bottomAlign"><b><a href="qlinkedlist-const-iterator.html#operator--">operator--</a></b> ()</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> const_iterator </td><td class="memItemRight bottomAlign"><b><a href="qlinkedlist-const-iterator.html#operator---2">operator--</a></b> ( int )</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> const_iterator & </td><td class="memItemRight bottomAlign"><b><a href="qlinkedlist-const-iterator.html#operator--eq">operator-=</a></b> ( int <i>j</i> )</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> const T * </td><td class="memItemRight bottomAlign"><b><a href="qlinkedlist-const-iterator.html#operator--gt">operator-></a></b> () const</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> const_iterator & </td><td class="memItemRight bottomAlign"><b><a href="qlinkedlist-const-iterator.html#operator-eq">operator=</a></b> ( const const_iterator & <i>other</i> )</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> bool </td><td class="memItemRight bottomAlign"><b><a href="qlinkedlist-const-iterator.html#operator-eq-eq">operator==</a></b> ( const const_iterator & <i>other</i> ) const</td></tr>
</table>
<a name="details"></a>
<!-- $$$const_iterator-description -->
<div class="descr">
<h2>Detailed Description</h2>
<p>The QLinkedList::const_iterator class provides an STL-style const iterator for <a href="qlinkedlist.html">QLinkedList</a>.</p>
<p><a href="qlinkedlist.html">QLinkedList</a> features both <a href="containers.html#stl-style-iterators">STL-style iterators</a> and <a href="containers.html#java-style-iterators">Java-style iterators</a>. The STL-style iterators are more low-level and more cumbersome to use; on the other hand, they are slightly faster and, for developers who already know STL, have the advantage of familiarity.</p>
<p><a href="qlinkedlist.html">QLinkedList</a><T>::const_iterator allows you to iterate over a <a href="qlinkedlist.html">QLinkedList</a><T>. If you want modify the <a href="qlinkedlist.html">QLinkedList</a> as you iterate over it, you must use <a href="qlinkedlist-iterator.html">QLinkedList::iterator</a> instead. It is generally good practice to use QLinkedList::const_iterator on a non-const <a href="qlinkedlist.html">QLinkedList</a> as well, unless you need to change the <a href="qlinkedlist.html">QLinkedList</a> through the iterator. Const iterators are slightly faster, and can improve code readability.</p>
<p>The default QLinkedList::const_iterator constructor creates an uninitialized iterator. You must initialize it using a function like <a href="qlinkedlist.html#constBegin">QLinkedList::constBegin</a>(), <a href="qlinkedlist.html#constEnd">QLinkedList::constEnd</a>(), or <a href="qlinkedlist.html#insert">QLinkedList::insert</a>() before you can start iterating. Here's a typical loop that prints all the items stored in a list:</p>
<pre class="cpp"> <span class="type"><a href="qlinkedlist.html">QLinkedList</a></span><span class="operator"><</span><span class="type"><a href="qstring.html">QString</a></span><span class="operator">></span> list;
list<span class="operator">.</span><a href="qlinkedlist.html#append">append</a>(<span class="string">"January"</span>);
list<span class="operator">.</span><a href="qlinkedlist.html#append">append</a>(<span class="string">"February"</span>);
<span class="operator">.</span><span class="operator">.</span><span class="operator">.</span>
list<span class="operator">.</span><a href="qlinkedlist.html#append">append</a>(<span class="string">"December"</span>);
<span class="type"><a href="qlinkedlist.html">QLinkedList</a></span><span class="operator"><</span><span class="type"><a href="qstring.html">QString</a></span><span class="operator">></span><span class="operator">::</span>const_iterator i;
<span class="keyword">for</span> (i <span class="operator">=</span> list<span class="operator">.</span>constBegin(); i <span class="operator">!</span><span class="operator">=</span> list<span class="operator">.</span>constEnd(); <span class="operator">+</span><span class="operator">+</span>i)
cout <span class="operator"><</span><span class="operator"><</span> <span class="operator">*</span>i <span class="operator"><</span><span class="operator"><</span> endl;</pre>
<p>STL-style iterators can be used as arguments to <a href="qtalgorithms.html">generic algorithms</a>. For example, here's how to find an item in the list using the <a href="qtalgorithms.html#qFind">qFind</a>() algorithm:</p>
<pre class="cpp"> <span class="type"><a href="qlinkedlist.html">QLinkedList</a></span><span class="operator"><</span><span class="type"><a href="qstring.html">QString</a></span><span class="operator">></span> list;
<span class="operator">.</span><span class="operator">.</span><span class="operator">.</span>
<span class="type"><a href="qlinkedlist.html">QLinkedList</a></span><span class="operator"><</span><span class="type"><a href="qstring.html">QString</a></span><span class="operator">></span><span class="operator">::</span>iterator it <span class="operator">=</span> <a href="qtalgorithms.html#qFind">qFind</a>(list<span class="operator">.</span>constBegin()<span class="operator">,</span>
list<span class="operator">.</span>constEnd()<span class="operator">,</span> <span class="string">"Joel"</span>);
<span class="keyword">if</span> (it <span class="operator">!</span><span class="operator">=</span> list<span class="operator">.</span>constEnd())
cout <span class="operator"><</span><span class="operator"><</span> <span class="string">"Found Joel"</span> <span class="operator"><</span><span class="operator"><</span> endl;</pre>
<p>Multiple iterators can be used on the same list. If you add items to the list, existing iterators will remain valid. If you remove items from the list, iterators that point to the removed items will become dangling iterators.</p>
</div>
<p><b>See also </b><a href="qlinkedlist-iterator.html">QLinkedList::iterator</a> and <a href="qlinkedlistiterator.html">QLinkedListIterator</a>.</p>
<!-- @@@const_iterator -->
<div class="func">
<h2>Member Function Documentation</h2>
<!-- $$$const_iterator[overload1]$$$const_iterator -->
<h3 class="fn"><a name="const_iterator"></a>const_iterator::<span class="name">const_iterator</span> ()</h3>
<p>Constructs an uninitialized iterator.</p>
<p>Functions like operator*() and operator++() should not be called on an uninitialized iterator. Use operator=() to assign a value to it before using it.</p>
<p><b>See also </b><a href="qlinkedlist.html#constBegin">QLinkedList::constBegin</a>() and <a href="qlinkedlist.html#constEnd">QLinkedList::constEnd</a>().</p>
<!-- @@@const_iterator -->
<!-- $$$const_iterator$$$const_iteratorconstconst_iterator& -->
<h3 class="fn"><a name="const_iterator-3"></a>const_iterator::<span class="name">const_iterator</span> ( const <span class="type">const_iterator</span> & <i>other</i> )</h3>
<p>Constructs a copy of <i>other</i>.</p>
<!-- @@@const_iterator -->
<!-- $$$const_iterator$$$const_iteratoriterator -->
<h3 class="fn"><a name="const_iterator-4"></a>const_iterator::<span class="name">const_iterator</span> ( <span class="type"><a href="qlinkedlist-iterator.html">iterator</a></span> <i>other</i> )</h3>
<p>Constructs a copy of <i>other</i>.</p>
<!-- @@@const_iterator -->
<!-- $$$operator!=[overload1]$$$operator!=constconst_iterator& -->
<h3 class="fn"><a name="operator-not-eq"></a><span class="type">bool</span> const_iterator::<span class="name">operator!=</span> ( const <span class="type">const_iterator</span> & <i>other</i> ) const</h3>
<p>Returns true if <i>other</i> points to a different item than this iterator; otherwise returns false.</p>
<p><b>See also </b><a href="qlinkedlist-const-iterator.html#operator-eq-eq">operator==</a>().</p>
<!-- @@@operator!= -->
<!-- $$$operator*[overload1]$$$operator* -->
<h3 class="fn"><a name="operator-2a"></a>const <span class="type">T</span> & const_iterator::<span class="name">operator*</span> () const</h3>
<p>Returns a reference to the current item.</p>
<p><b>See also </b><a href="qlinkedlist-const-iterator.html#operator--gt">operator-></a>().</p>
<!-- @@@operator* -->
<!-- $$$operator+[overload1]$$$operator+int -->
<h3 class="fn"><a name="operator-2b"></a><span class="type">const_iterator</span> const_iterator::<span class="name">operator+</span> ( <span class="type">int</span> <i>j</i> ) const</h3>
<p>Returns an iterator to the item at <i>j</i> positions forward from this iterator. (If <i>j</i> is negative, the iterator goes backward.)</p>
<p>This operation can be slow for large <i>j</i> values.</p>
<p><b>See also </b><a href="qlinkedlist-const-iterator.html#operator-">operator-</a>().</p>
<!-- @@@operator+ -->
<!-- $$$operator++[overload1]$$$operator++ -->
<h3 class="fn"><a name="operator-2b-2b"></a><span class="type">const_iterator</span> & const_iterator::<span class="name">operator++</span> ()</h3>
<p>The prefix ++ operator (<tt>++it</tt>) advances the iterator to the next item in the list and returns an iterator to the new current item.</p>
<p>Calling this function on <a href="qlinkedlist.html#constEnd">QLinkedList::constEnd</a>() leads to undefined results.</p>
<p><b>See also </b><a href="qlinkedlist-const-iterator.html#operator--">operator--</a>().</p>
<!-- @@@operator++ -->
<!-- $$$operator++$$$operator++int -->
<h3 class="fn"><a name="operator-2b-2b-2"></a><span class="type">const_iterator</span> const_iterator::<span class="name">operator++</span> ( <span class="type">int</span> )</h3>
<p>This is an overloaded function.</p>
<p>The postfix ++ operator (<tt>it++</tt>) advances the iterator to the next item in the list and returns an iterator to the previously current item.</p>
<!-- @@@operator++ -->
<!-- $$$operator+=[overload1]$$$operator+=int -->
<h3 class="fn"><a name="operator-2b-eq"></a><span class="type">const_iterator</span> & const_iterator::<span class="name">operator+=</span> ( <span class="type">int</span> <i>j</i> )</h3>
<p>Advances the iterator by <i>j</i> items. (If <i>j</i> is negative, the iterator goes backward.)</p>
<p>This operation can be slow for large <i>j</i> values.</p>
<p><b>See also </b><a href="qlinkedlist-const-iterator.html#operator--eq">operator-=</a>() and <a href="qlinkedlist-const-iterator.html#operator-2b">operator+</a>().</p>
<!-- @@@operator+= -->
<!-- $$$operator-[overload1]$$$operator-int -->
<h3 class="fn"><a name="operator-"></a><span class="type">const_iterator</span> const_iterator::<span class="name">operator-</span> ( <span class="type">int</span> <i>j</i> ) const</h3>
<p>This function returns an iterator to the item at <i>j</i> positions backward from this iterator. (If <i>j</i> is negative, the iterator goes forward.)</p>
<p>This operation can be slow for large <i>j</i> values.</p>
<p><b>See also </b><a href="qlinkedlist-const-iterator.html#operator-2b">operator+</a>().</p>
<!-- @@@operator- -->
<!-- $$$operator--[overload1]$$$operator-- -->
<h3 class="fn"><a name="operator--"></a><span class="type">const_iterator</span> & const_iterator::<span class="name">operator--</span> ()</h3>
<p>The prefix -- operator (<tt>--it</tt>) makes the preceding item current and returns an iterator to the new current item.</p>
<p>Calling this function on <a href="qlinkedlist.html#begin">QLinkedList::begin</a>() leads to undefined results.</p>
<p><b>See also </b><a href="qlinkedlist-const-iterator.html#operator-2b-2b">operator++</a>().</p>
<!-- @@@operator-- -->
<!-- $$$operator--$$$operator--int -->
<h3 class="fn"><a name="operator---2"></a><span class="type">const_iterator</span> const_iterator::<span class="name">operator--</span> ( <span class="type">int</span> )</h3>
<p>This is an overloaded function.</p>
<p>The postfix -- operator (<tt>it--</tt>) makes the preceding item current and returns an iterator to the previously current item.</p>
<!-- @@@operator-- -->
<!-- $$$operator-=[overload1]$$$operator-=int -->
<h3 class="fn"><a name="operator--eq"></a><span class="type">const_iterator</span> & const_iterator::<span class="name">operator-=</span> ( <span class="type">int</span> <i>j</i> )</h3>
<p>Makes the iterator go back by <i>j</i> items. (If <i>j</i> is negative, the iterator goes forward.)</p>
<p>This operation can be slow for large <i>j</i> values.</p>
<p><b>See also </b><a href="qlinkedlist-const-iterator.html#operator-2b-eq">operator+=</a>() and <a href="qlinkedlist-const-iterator.html#operator-">operator-</a>().</p>
<!-- @@@operator-= -->
<!-- $$$operator->[overload1]$$$operator-> -->
<h3 class="fn"><a name="operator--gt"></a>const <span class="type">T</span> * const_iterator::<span class="name">operator-></span> () const</h3>
<p>Returns a pointer to the current item.</p>
<p><b>See also </b><a href="qlinkedlist-const-iterator.html#operator-2a">operator*</a>().</p>
<!-- @@@operator-> -->
<!-- $$$operator=[overload1]$$$operator=constconst_iterator& -->
<h3 class="fn"><a name="operator-eq"></a><span class="type">const_iterator</span> & const_iterator::<span class="name">operator=</span> ( const <span class="type">const_iterator</span> & <i>other</i> )</h3>
<p>Assigns <i>other</i> to this iterator.</p>
<!-- @@@operator= -->
<!-- $$$operator==[overload1]$$$operator==constconst_iterator& -->
<h3 class="fn"><a name="operator-eq-eq"></a><span class="type">bool</span> const_iterator::<span class="name">operator==</span> ( const <span class="type">const_iterator</span> & <i>other</i> ) const</h3>
<p>Returns true if <i>other</i> points to the same item as this iterator; otherwise returns false.</p>
<p><b>See also </b><a href="qlinkedlist-const-iterator.html#operator-not-eq">operator!=</a>().</p>
<!-- @@@operator== -->
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