1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
|
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en_US" lang="en_US">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<!-- qmap.cpp -->
<title>Qt 4.8: const_iterator Class Reference</title>
<link rel="stylesheet" type="text/css" href="style/offline.css" />
</head>
<body>
<div class="header" id="qtdocheader">
<div class="content">
<a href="index.html" class="qtref"><span>Qt Reference Documentation</span></a>
</div>
<div class="breadcrumb toolblock">
<ul>
<li class="first"><a href="index.html">Home</a></li>
<!-- Breadcrumbs go here -->
<li><a href="modules.html">Modules</a></li>
<li><a href="qtcore.html">QtCore</a></li>
<li>const_iterator</li>
</ul>
</div>
</div>
<div class="content mainContent">
<div class="toc">
<h3><a name="toc">Contents</a></h3>
<ul>
<li class="level1"><a href="#public-types">Public Types</a></li>
<li class="level1"><a href="#public-functions">Public Functions</a></li>
<li class="level1"><a href="#details">Detailed Description</a></li>
</ul>
</div>
<h1 class="title">const_iterator Class Reference</h1>
<span class="small-subtitle">(QMap::const_iterator)<br/></span>
<!-- $$$const_iterator-brief -->
<p>The QMap::const_iterator class provides an STL-style const iterator for <a href="qmap.html">QMap</a> and <a href="qmultimap.html">QMultiMap</a>. <a href="#details">More...</a></p>
<!-- @@@const_iterator -->
<pre class="cpp"> <span class="preprocessor">#include <<a href="qmap.html">QMap</a>></span></pre><ul>
<li><a href="qmap-const-iterator-members.html">List of all members, including inherited members</a></li>
<li><a href="qmap-const-iterator-qt3.html">Qt 3 support members</a></li>
</ul>
<a name="public-types"></a>
<h2>Public Types</h2>
<table class="alignedsummary">
<tr><td class="memItemLeft rightAlign topAlign"> typedef </td><td class="memItemRight bottomAlign"><b><a href="qmap-const-iterator.html#iterator_category-typedef">iterator_category</a></b></td></tr>
</table>
<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="qmap-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="qmap-const-iterator.html#const_iterator-3">const_iterator</a></b> ( const iterator & <i>other</i> )</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> const Key & </td><td class="memItemRight bottomAlign"><b><a href="qmap-const-iterator.html#key">key</a></b> () const</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> const T & </td><td class="memItemRight bottomAlign"><b><a href="qmap-const-iterator.html#value">value</a></b> () const</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> bool </td><td class="memItemRight bottomAlign"><b><a href="qmap-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="qmap-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="qmap-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="qmap-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="qmap-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="qmap-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="qmap-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="qmap-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="qmap-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="qmap-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="qmap-const-iterator.html#operator--gt">operator-></a></b> () const</td></tr>
<tr><td class="memItemLeft rightAlign topAlign"> bool </td><td class="memItemRight bottomAlign"><b><a href="qmap-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 QMap::const_iterator class provides an STL-style const iterator for <a href="qmap.html">QMap</a> and <a href="qmultimap.html">QMultiMap</a>.</p>
<p><a href="qmap.html">QMap</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="qmap.html">QMap</a><Key, T>::const_iterator allows you to iterate over a <a href="qmap.html">QMap</a> (or a <a href="qmultimap.html">QMultiMap</a>). If you want to modify the <a href="qmap.html">QMap</a> as you iterate over it, you must use <a href="qmap-iterator.html">QMap::iterator</a> instead. It is generally good practice to use QMap::const_iterator on a non-const <a href="qmap.html">QMap</a> as well, unless you need to change the <a href="qmap.html">QMap</a> through the iterator. Const iterators are slightly faster, and can improve code readability.</p>
<p>The default QMap::const_iterator constructor creates an uninitialized iterator. You must initialize it using a <a href="qmap.html">QMap</a> function like <a href="qmap.html#constBegin">QMap::constBegin</a>(), <a href="qmap.html#constEnd">QMap::constEnd</a>(), or <a href="qmap.html#find">QMap::find</a>() before you can start iterating. Here's a typical loop that prints all the (key, value) pairs stored in a map:</p>
<pre class="cpp"> <span class="type"><a href="qmap.html">QMap</a></span><span class="operator"><</span><span class="type"><a href="qstring.html">QString</a></span><span class="operator">,</span> <span class="type">int</span><span class="operator">></span> map;
map<span class="operator">.</span><a href="qmap.html#insert">insert</a>(<span class="string">"January"</span><span class="operator">,</span> <span class="number">1</span>);
map<span class="operator">.</span><a href="qmap.html#insert">insert</a>(<span class="string">"February"</span><span class="operator">,</span> <span class="number">2</span>);
<span class="operator">.</span><span class="operator">.</span><span class="operator">.</span>
map<span class="operator">.</span><a href="qmap.html#insert">insert</a>(<span class="string">"December"</span><span class="operator">,</span> <span class="number">12</span>);
<span class="type"><a href="qmap.html">QMap</a></span><span class="operator"><</span><span class="type"><a href="qstring.html">QString</a></span><span class="operator">,</span> <span class="type">int</span><span class="operator">></span><span class="operator">::</span>const_iterator i;
<span class="keyword">for</span> (i <span class="operator">=</span> map<span class="operator">.</span>constBegin(); i <span class="operator">!</span><span class="operator">=</span> map<span class="operator">.</span>constEnd(); <span class="operator">+</span><span class="operator">+</span>i)
cout <span class="operator"><</span><span class="operator"><</span> i<span class="operator">.</span><a href="qmap-const-iterator.html#key">key</a>() <span class="operator"><</span><span class="operator"><</span> <span class="string">": "</span> <span class="operator"><</span><span class="operator"><</span> i<span class="operator">.</span><a href="qmap-const-iterator.html#value">value</a>() <span class="operator"><</span><span class="operator"><</span> endl;</pre>
<p>Unlike <a href="qhash.html">QHash</a>, which stores its items in an arbitrary order, <a href="qmap.html">QMap</a> stores its items ordered by key. Items that share the same key (because they were inserted using <a href="qmap.html#insertMulti">QMap::insertMulti</a>()) will appear consecutively, from the most recently to the least recently inserted value.</p>
<p>Multiple iterators can be used on the same map. If you add items to the map, existing iterators will remain valid. If you remove items from the map, iterators that point to the removed items will become dangling iterators.</p>
</div>
<p><b>See also </b><a href="qmap-iterator.html">QMap::iterator</a> and <a href="qmapiterator.html">QMapIterator</a>.</p>
<!-- @@@const_iterator -->
<div class="types">
<h2>Member Type Documentation</h2>
<!-- $$$iterator_category -->
<h3 class="fn"><a name="iterator_category-typedef"></a>typedef const_iterator::<span class="name">iterator_category</span></h3>
<p>A synonym for <i>std::bidirectional_iterator_tag</i> indicating this iterator is a bidirectional iterator.</p>
<!-- @@@iterator_category -->
</div>
<div class="func">
<h2>Member Function Documentation</h2>
<!-- $$$const_iterator[overload1]$$$const_iterator -->
<h3 class="fn"><a name="const_iterator"></a>const_iterator::<span class="name">const_iterator</span> ()</h3>
<p>Constructs an uninitialized iterator.</p>
<p>Functions like <a href="qmap-const-iterator.html#key">key</a>(), <a href="qmap-const-iterator.html#value">value</a>(), and operator++() must not be called on an uninitialized iterator. Use operator=() to assign a value to it before using it.</p>
<p><b>See also </b><a href="qmap.html#constBegin">QMap::constBegin</a>() and <a href="qmap.html#constEnd">QMap::constEnd</a>().</p>
<!-- @@@const_iterator -->
<!-- $$$const_iterator$$$const_iteratorconstiterator& -->
<h3 class="fn"><a name="const_iterator-3"></a>const_iterator::<span class="name">const_iterator</span> ( const <span class="type"><a href="qmap-iterator.html">iterator</a></span> & <i>other</i> )</h3>
<p>Constructs a copy of <i>other</i>.</p>
<!-- @@@const_iterator -->
<!-- $$$key[overload1]$$$key -->
<h3 class="fn"><a name="key"></a>const <span class="type">Key</span> & const_iterator::<span class="name">key</span> () const</h3>
<p>Returns the current item's key.</p>
<p><b>See also </b><a href="qmap-const-iterator.html#value">value</a>().</p>
<!-- @@@key -->
<!-- $$$value[overload1]$$$value -->
<h3 class="fn"><a name="value"></a>const <span class="type">T</span> & const_iterator::<span class="name">value</span> () const</h3>
<p>Returns the current item's value.</p>
<p><b>See also </b><a href="qmap-const-iterator.html#key">key</a>() and <a href="qmap-const-iterator.html#operator-2a">operator*</a>().</p>
<!-- @@@value -->
<!-- $$$operator!=[overload1]$$$operator!=constconst_iterator& -->
<h3 class="fn"><a name="operator-not-eq"></a><span class="type">bool</span> const_iterator::<span class="name">operator!=</span> ( const <span class="type">const_iterator</span> & <i>other</i> ) const</h3>
<p>Returns true if <i>other</i> points to a different item than this iterator; otherwise returns false.</p>
<p><b>See also </b><a href="qmap-const-iterator.html#operator-eq-eq">operator==</a>().</p>
<!-- @@@operator!= -->
<!-- $$$operator*[overload1]$$$operator* -->
<h3 class="fn"><a name="operator-2a"></a>const <span class="type">T</span> & const_iterator::<span class="name">operator*</span> () const</h3>
<p>Returns the current item's value.</p>
<p>Same as <a href="qmap-const-iterator.html#value">value</a>().</p>
<p><b>See also </b><a href="qmap-const-iterator.html#key">key</a>().</p>
<!-- @@@operator* -->
<!-- $$$operator+[overload1]$$$operator+int -->
<h3 class="fn"><a name="operator-2b"></a><span class="type">const_iterator</span> const_iterator::<span class="name">operator+</span> ( <span class="type">int</span> <i>j</i> ) const</h3>
<p>Returns an iterator to the item at <i>j</i> positions forward from this iterator. (If <i>j</i> is negative, the iterator goes backward.)</p>
<p>This operation can be slow for large <i>j</i> values.</p>
<p><b>See also </b><a href="qmap-const-iterator.html#operator-">operator-</a>().</p>
<!-- @@@operator+ -->
<!-- $$$operator++[overload1]$$$operator++ -->
<h3 class="fn"><a name="operator-2b-2b"></a><span class="type">const_iterator</span> & const_iterator::<span class="name">operator++</span> ()</h3>
<p>The prefix ++ operator (<tt>++i</tt>) advances the iterator to the next item in the map and returns an iterator to the new current item.</p>
<p>Calling this function on <a href="qmap.html#end">QMap::end</a>() leads to undefined results.</p>
<p><b>See also </b><a href="qmap-const-iterator.html#operator--">operator--</a>().</p>
<!-- @@@operator++ -->
<!-- $$$operator++$$$operator++int -->
<h3 class="fn"><a name="operator-2b-2b-2"></a><span class="type">const_iterator</span> const_iterator::<span class="name">operator++</span> ( <span class="type">int</span> )</h3>
<p>This is an overloaded function.</p>
<p>The postfix ++ operator (<tt>i++</tt>) advances the iterator to the next item in the map and returns an iterator to the previously current item.</p>
<!-- @@@operator++ -->
<!-- $$$operator+=[overload1]$$$operator+=int -->
<h3 class="fn"><a name="operator-2b-eq"></a><span class="type">const_iterator</span> & const_iterator::<span class="name">operator+=</span> ( <span class="type">int</span> <i>j</i> )</h3>
<p>Advances the iterator by <i>j</i> items. (If <i>j</i> is negative, the iterator goes backward.)</p>
<p>This operation can be slow for large <i>j</i> values.</p>
<p><b>See also </b><a href="qmap-const-iterator.html#operator--eq">operator-=</a>() and <a href="qmap-const-iterator.html#operator-2b">operator+</a>().</p>
<!-- @@@operator+= -->
<!-- $$$operator-[overload1]$$$operator-int -->
<h3 class="fn"><a name="operator-"></a><span class="type">const_iterator</span> const_iterator::<span class="name">operator-</span> ( <span class="type">int</span> <i>j</i> ) const</h3>
<p>Returns an iterator to the item at <i>j</i> positions backward from this iterator. (If <i>j</i> is negative, the iterator goes forward.)</p>
<p>This operation can be slow for large <i>j</i> values.</p>
<p><b>See also </b><a href="qmap-const-iterator.html#operator-2b">operator+</a>().</p>
<!-- @@@operator- -->
<!-- $$$operator--[overload1]$$$operator-- -->
<h3 class="fn"><a name="operator--"></a><span class="type">const_iterator</span> & const_iterator::<span class="name">operator--</span> ()</h3>
<p>The prefix -- operator (<tt>--i</tt>) makes the preceding item current and returns an iterator pointing to the new current item.</p>
<p>Calling this function on <a href="qmap.html#begin">QMap::begin</a>() leads to undefined results.</p>
<p><b>See also </b><a href="qmap-const-iterator.html#operator-2b-2b">operator++</a>().</p>
<!-- @@@operator-- -->
<!-- $$$operator--$$$operator--int -->
<h3 class="fn"><a name="operator---2"></a><span class="type">const_iterator</span> const_iterator::<span class="name">operator--</span> ( <span class="type">int</span> )</h3>
<p>This is an overloaded function.</p>
<p>The postfix -- operator (<tt>i--</tt>) makes the preceding item current and returns an iterator pointing to the previously current item.</p>
<!-- @@@operator-- -->
<!-- $$$operator-=[overload1]$$$operator-=int -->
<h3 class="fn"><a name="operator--eq"></a><span class="type">const_iterator</span> & const_iterator::<span class="name">operator-=</span> ( <span class="type">int</span> <i>j</i> )</h3>
<p>Makes the iterator go back by <i>j</i> items. (If <i>j</i> is negative, the iterator goes forward.)</p>
<p>This operation can be slow for large <i>j</i> values.</p>
<p><b>See also </b><a href="qmap-const-iterator.html#operator-2b-eq">operator+=</a>() and <a href="qmap-const-iterator.html#operator-">operator-</a>().</p>
<!-- @@@operator-= -->
<!-- $$$operator->[overload1]$$$operator-> -->
<h3 class="fn"><a name="operator--gt"></a>const <span class="type">T</span> * const_iterator::<span class="name">operator-></span> () const</h3>
<p>Returns a pointer to the current item's value.</p>
<p><b>See also </b><a href="qmap-const-iterator.html#value">value</a>().</p>
<!-- @@@operator-> -->
<!-- $$$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="qmap-const-iterator.html#operator-not-eq">operator!=</a>().</p>
<!-- @@@operator== -->
</div>
<div class="ft">
<span></span>
</div>
</div>
<div class="footer">
<p>
<acronym title="Copyright">©</acronym> 2012 Nokia Corporation and/or its
subsidiaries. Documentation contributions included herein are the copyrights of
their respective owners.</p>
<br />
<p>
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.</p>
<p>
Documentation sources may be obtained from <a href="http://www.qt-project.org">
www.qt-project.org</a>.</p>
<br />
<p>
Nokia, Qt and their respective logos are trademarks of Nokia Corporation
in Finland and/or other countries worldwide. All other trademarks are property
of their respective owners. <a title="Privacy Policy"
href="http://en.gitorious.org/privacy_policy/">Privacy Policy</a></p>
</div>
</body>
</html>
|
