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
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
|
<!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=US-ASCII">
<title>Concept RandomAccessIterator</title>
<link rel="stylesheet" href="../../doc/src/boostbook.css" type="text/css">
<meta name="generator" content="DocBook XSL Stylesheets V1.79.1">
<link rel="home" href="index.html" title="The Boost C++ Libraries BoostBook Documentation Subset">
<link rel="up" href="concept_check.html#concepts.reference" title="Concept reference">
<link rel="prev" href="BidirectionalIterator.html" title="Concept BidirectionalIterator">
<link rel="next" href="DefaultConstructible.html" title="Concept DefaultConstructible">
</head>
<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF">
<table cellpadding="2" width="100%"><tr>
<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../boost.png"></td>
<td align="center"><a href="../../index.html">Home</a></td>
<td align="center"><a href="../../libs/libraries.htm">Libraries</a></td>
<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td>
<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td>
<td align="center"><a href="../../more/index.htm">More</a></td>
</tr></table>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="BidirectionalIterator.html"><img src="../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="concept_check.html#concepts.reference"><img src="../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="index.html"><img src="../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="DefaultConstructible.html"><img src="../../doc/src/images/next.png" alt="Next"></a>
</div>
<div class="refentry">
<a name="RandomAccessIterator"></a><div class="titlepage"></div>
<div class="refnamediv">
<h2><span class="refentrytitle">Concept RandomAccessIterator</span></h2>
<p>RandomAccessIterator</p>
</div>
<div class="refsect1">
<a name="id-1.3.49.3.9.3"></a><h2>Description</h2>
<p>A random access iterator is an iterator that can read through
a sequence of values. It can move in either direction through the
sequence (by any amount in constant time), 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">
<a name="id-1.3.49.3.9.4"></a><h2>Refinement of</h2>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem"><p><a class="link" href="BidirectionalIterator.html" title="Concept BidirectionalIterator">BidirectionalIterator</a></p></li>
<li class="listitem"><p><a class="link" href="LessThanComparable.html" title="Concept LessThanComparable">LessThanComparable</a></p></li>
</ul></div>
</div>
<div class="refsect1">
<a name="id-1.3.49.3.9.5"></a><h2>Associated types</h2>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem">
<p><span class="bold"><strong>value_type</strong></span></p>
<pre class="literallayout">std::iterator_traits<Iter>::value_type</pre>
<p>The value type of the iterator</p>
</li>
<li class="listitem">
<p><span class="bold"><strong>category</strong></span></p>
<pre class="literallayout">std::iterator_traits<Iter>::iterator_category</pre>
<p>The category of the iterator</p>
</li>
<li class="listitem">
<p><span class="bold"><strong>difference_type</strong></span></p>
<pre class="literallayout">std::iterator_traits<Iter>::difference_type</pre>
<p>The difference type of the iterator (measure of the number
of steps between two iterators)</p>
</li>
</ul></div>
</div>
<div class="refsect1">
<a name="id-1.3.49.3.9.6"></a><h2>Notation</h2>
<div class="variablelist"><dl class="variablelist">
<dt><span class="term">Iter</span></dt>
<dd>A type playing the role of iterator-type in the <a class="link" href="RandomAccessIterator.html" title="Concept RandomAccessIterator">RandomAccessIterator</a> concept.</dd>
<dt>
<span class="term"><code class="varname">i</code>, </span><span class="term"><code class="varname">j</code></span>
</dt>
<dd>Objects of type Iter</dd>
<dt><span class="term"><code class="varname">x</code></span></dt>
<dd>Object of type value_type</dd>
<dt><span class="term"><code class="varname">n</code></span></dt>
<dd>Object of type difference_type</dd>
<dt><span class="term"><code class="varname">int_off</code></span></dt>
<dd>Object of type int</dd>
</dl></div>
</div>
<div class="refsect1">
<a name="id-1.3.49.3.9.7"></a><h2>Type expressions</h2>
<div class="variablelist"><dl class="variablelist">
<dt><span class="term">Category tag</span></dt>
<dd><p><span class="type">category</span> must be
derived from <span class="type">std::random_access_iterator_tag</span>.
</p></dd>
</dl></div>
</div>
<div class="refsect1">
<a name="id-1.3.49.3.9.8"></a><h2>Valid expressions</h2>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
<col>
<col>
</colgroup>
<thead><tr>
<th>Name</th>
<th>Expression</th>
<th>Type</th>
<th>Semantics</th>
</tr></thead>
<tbody>
<tr>
<td><p>Motion</p></td>
<td><p>i += n</p></td>
<td><p><span class="type">Iter &</span></p></td>
<td><p>Equivalent to applying <code class="computeroutput">i++</code> <code class="computeroutput">n</code> times
if <code class="computeroutput">n</code> is positive, applying <code class="computeroutput">i--</code>
<code class="computeroutput">-n</code> times if <code class="computeroutput">n</code> is negative, and to a null
operation if <code class="computeroutput">n</code> is zero.</p></td>
</tr>
<tr>
<td><p>Motion (with integer offset)</p></td>
<td><p>i += int_off</p></td>
<td><p><span class="type">Iter &</span></p></td>
<td><p>Equivalent to applying <code class="computeroutput">i++</code> <code class="computeroutput">n</code> times
if <code class="computeroutput">n</code> is positive, applying <code class="computeroutput">i--</code>
<code class="computeroutput">-n</code> times if <code class="computeroutput">n</code> is negative, and to a null
operation if <code class="computeroutput">n</code> is zero.</p></td>
</tr>
<tr>
<td><p>Subtractive motion</p></td>
<td><p>i -= n</p></td>
<td><p><span class="type">Iter &</span></p></td>
<td><p>Equivalent to <code class="computeroutput">i+=(-n)</code></p></td>
</tr>
<tr>
<td><p>Subtractive motion (with integer offset)</p></td>
<td><p>i -= int_off</p></td>
<td><p><span class="type">Iter &</span></p></td>
<td><p>Equivalent to <code class="computeroutput">i+=(-n)</code></p></td>
</tr>
<tr>
<td><p>Addition</p></td>
<td><p>i + n</p></td>
<td><p><span class="type">Iter</span></p></td>
<td><p>Equivalent to <code class="computeroutput">{Iter j = i; j += n; return j;}</code></p></td>
</tr>
<tr>
<td><p>Addition with integer</p></td>
<td><p>i + int_off</p></td>
<td><p><span class="type">Iter</span></p></td>
<td><p>Equivalent to <code class="computeroutput">{Iter j = i; j += n; return j;}</code></p></td>
</tr>
<tr>
<td><p>Addition (count first)</p></td>
<td><p>n + i</p></td>
<td><p><span class="type">Iter</span></p></td>
<td><p>Equivalent to <code class="computeroutput">i + n</code></p></td>
</tr>
<tr>
<td><p>Addition with integer (count first)</p></td>
<td><p>int_off + i</p></td>
<td><p><span class="type">Iter</span></p></td>
<td><p>Equivalent to <code class="computeroutput">i + n</code></p></td>
</tr>
<tr>
<td><p>Subtraction</p></td>
<td><p>i - n</p></td>
<td><p><span class="type">Iter</span></p></td>
<td><p>Equivalent to <code class="computeroutput">i + (-n)</code></p></td>
</tr>
<tr>
<td><p>Subtraction with integer</p></td>
<td><p>i - int_off</p></td>
<td><p><span class="type">Iter</span></p></td>
<td><p>Equivalent to <code class="computeroutput">i + (-n)</code></p></td>
</tr>
<tr>
<td><p>Distance</p></td>
<td><p>i - j</p></td>
<td><p><span class="type">difference_type</span></p></td>
<td><p>The number of times <code class="computeroutput">i</code> must be incremented (or
decremented if the result is negative) to reach <code class="computeroutput">j</code>. Not
defined if <code class="computeroutput">j</code> is not reachable from
<code class="computeroutput">i</code>.</p></td>
</tr>
<tr>
<td><p>Element access</p></td>
<td><p>i[n]</p></td>
<td><p><span class="type">const-if-not-mutable value_type &</span></p></td>
<td><p>Equivalent to <code class="computeroutput">*(i + n)</code></p></td>
</tr>
<tr>
<td><p>Element access with integer index</p></td>
<td><p>i[int_off]</p></td>
<td><p><span class="type">const-if-not-mutable value_type &</span></p></td>
<td><p>Equivalent to <code class="computeroutput">*(i + n)</code></p></td>
</tr>
</tbody>
</table></div>
</div>
<div class="refsect1">
<a name="id-1.3.49.3.9.9"></a><h2>Complexity</h2>
<p>
All iterator operations must take amortized constant time.
</p>
</div>
<div class="refsect1">
<a name="id-1.3.49.3.9.10"></a><h2>Models</h2>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; ">
<li class="listitem"><span class="simplelist"><span class="type">T *</span></span></li>
<li class="listitem"><span class="simplelist"><span class="type">std::vector<T>::iterator</span></span></li>
<li class="listitem"><span class="simplelist"><span class="type">std::vector<T>::const_iterator</span></span></li>
<li class="listitem"><span class="simplelist"><span class="type">std::deque<T>::iterator</span></span></li>
<li class="listitem"><span class="simplelist"><span class="type">std::deque<T>::const_iterator</span></span></li>
</ul></div>
</div>
<div class="refsect1">
<a name="id-1.3.49.3.9.11"></a><h2>See also</h2>
<div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p><a class="link" href="LessThanComparable.html" title="Concept LessThanComparable">LessThanComparable</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"></td>
<td align="right"><div class="copyright-footer">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<p>Distributed under the Boost Software License, Version 1.0.
(See accompanying file <code class="filename">LICENSE_1_0.txt</code> or copy at
<a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>)
</p>
<p>This product includes software developed at the University
of Notre Dame and the Pervasive Technology Labs at Indiana
University. For technical information contact Andrew Lumsdaine
at the Pervasive Technology Labs at Indiana University. For
administrative and license questions contact the Advanced
Research and Technology Institute at 351 West 10th Street.
Indianapolis, Indiana 46202, phone 317-278-4100, fax
317-274-5902.</p>
<p>Some concepts based on versions from the MTL draft manual
and Boost Graph and Property Map documentation, the SGI Standard
Template Library documentation and the Hewlett-Packard STL,
under the following license:
</p>
<div class="blockquote"><blockquote class="blockquote"><p>Permission to use, copy, modify, distribute and
sell this software and its documentation for any purpose is
hereby granted without fee, provided that the above copyright
notice appears in all copies and that both that copyright
notice and this permission notice appear in supporting
documentation. Silicon Graphics makes no representations
about the suitability of this software for any purpose. It is
provided "as is" without express or implied
warranty.</p></blockquote></div>
</div></td>
</tr></table>
<hr>
<div class="spirit-nav">
<a accesskey="p" href="BidirectionalIterator.html"><img src="../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="concept_check.html#concepts.reference"><img src="../../doc/src/images/up.png" alt="Up"></a><a accesskey="h" href="index.html"><img src="../../doc/src/images/home.png" alt="Home"></a><a accesskey="n" href="DefaultConstructible.html"><img src="../../doc/src/images/next.png" alt="Next"></a>
</div>
</body>
</html>
|
