1<html> 2<head> 3<meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> 4<title>length</title> 5<link rel="stylesheet" href="../../../../../../../../doc/src/boostbook.css" type="text/css"> 6<meta name="generator" content="DocBook XSL Stylesheets V1.79.1"> 7<link rel="home" href="../../../../index.html" title="Chapter 1. Geometry"> 8<link rel="up" href="../length.html" title="length"> 9<link rel="prev" href="../length.html" title="length"> 10<link rel="next" href="length_2_with_strategy.html" title="length (with strategy)"> 11</head> 12<body bgcolor="white" text="black" link="#0000FF" vlink="#840084" alink="#0000FF"> 13<table cellpadding="2" width="100%"><tr> 14<td valign="top"><img alt="Boost C++ Libraries" width="277" height="86" src="../../../../../../../../boost.png"></td> 15<td align="center"><a href="../../../../../../../../index.html">Home</a></td> 16<td align="center"><a href="../../../../../../../../libs/libraries.htm">Libraries</a></td> 17<td align="center"><a href="http://www.boost.org/users/people.html">People</a></td> 18<td align="center"><a href="http://www.boost.org/users/faq.html">FAQ</a></td> 19<td align="center"><a href="../../../../../../../../more/index.htm">More</a></td> 20</tr></table> 21<hr> 22<div class="spirit-nav"> 23<a accesskey="p" href="../length.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../length.html"><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="length_2_with_strategy.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> 24</div> 25<div class="section"> 26<div class="titlepage"><div><div><h5 class="title"> 27<a name="geometry.reference.algorithms.length.length_1"></a><a class="link" href="length_1.html" title="length">length</a> 28</h5></div></div></div> 29<p> 30 <a class="indexterm" name="idm45635693181024"></a> 31Calculates the length of a geometry. 32 </p> 33<h6> 34<a name="geometry.reference.algorithms.length.length_1.h0"></a> 35 <span class="phrase"><a name="geometry.reference.algorithms.length.length_1.description"></a></span><a class="link" href="length_1.html#geometry.reference.algorithms.length.length_1.description">Description</a> 36 </h6> 37<p> 38 The free function length calculates the length (the sum of distances 39 between consecutive points) of a geometry. It uses the default strategy, 40 based on the coordinate system of the geometry. 41 </p> 42<h6> 43<a name="geometry.reference.algorithms.length.length_1.h1"></a> 44 <span class="phrase"><a name="geometry.reference.algorithms.length.length_1.synopsis"></a></span><a class="link" href="length_1.html#geometry.reference.algorithms.length.length_1.synopsis">Synopsis</a> 45 </h6> 46<p> 47</p> 48<pre class="programlisting"><span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> <span class="identifier">Geometry</span><span class="special">></span> 49<span class="identifier">default_length_result</span><span class="special"><</span><span class="identifier">Geometry</span><span class="special">>::</span><span class="identifier">type</span> <span class="identifier">length</span><span class="special">(</span><span class="identifier">Geometry</span> <span class="keyword">const</span> <span class="special">&</span> <span class="identifier">geometry</span><span class="special">)</span></pre> 50<p> 51 </p> 52<h6> 53<a name="geometry.reference.algorithms.length.length_1.h2"></a> 54 <span class="phrase"><a name="geometry.reference.algorithms.length.length_1.parameters"></a></span><a class="link" href="length_1.html#geometry.reference.algorithms.length.length_1.parameters">Parameters</a> 55 </h6> 56<div class="informaltable"><table class="table"> 57<colgroup> 58<col> 59<col> 60<col> 61<col> 62</colgroup> 63<thead><tr> 64<th> 65 <p> 66 Type 67 </p> 68 </th> 69<th> 70 <p> 71 Concept 72 </p> 73 </th> 74<th> 75 <p> 76 Name 77 </p> 78 </th> 79<th> 80 <p> 81 Description 82 </p> 83 </th> 84</tr></thead> 85<tbody><tr> 86<td> 87 <p> 88 Geometry const & 89 </p> 90 </td> 91<td> 92 <p> 93 Any type fulfilling a Geometry Concept 94 </p> 95 </td> 96<td> 97 <p> 98 geometry 99 </p> 100 </td> 101<td> 102 <p> 103 A model of the specified concept 104 </p> 105 </td> 106</tr></tbody> 107</table></div> 108<h6> 109<a name="geometry.reference.algorithms.length.length_1.h3"></a> 110 <span class="phrase"><a name="geometry.reference.algorithms.length.length_1.returns"></a></span><a class="link" href="length_1.html#geometry.reference.algorithms.length.length_1.returns">Returns</a> 111 </h6> 112<p> 113 The calculated length 114 </p> 115<h6> 116<a name="geometry.reference.algorithms.length.length_1.h4"></a> 117 <span class="phrase"><a name="geometry.reference.algorithms.length.length_1.header"></a></span><a class="link" href="length_1.html#geometry.reference.algorithms.length.length_1.header">Header</a> 118 </h6> 119<p> 120 Either 121 </p> 122<p> 123 <code class="computeroutput"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span></code> 124 </p> 125<p> 126 Or 127 </p> 128<p> 129 <code class="computeroutput"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">/</span><span class="identifier">algorithms</span><span class="special">/</span><span class="identifier">length</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span></code> 130 </p> 131<h6> 132<a name="geometry.reference.algorithms.length.length_1.h5"></a> 133 <span class="phrase"><a name="geometry.reference.algorithms.length.length_1.conformance"></a></span><a class="link" href="length_1.html#geometry.reference.algorithms.length.length_1.conformance">Conformance</a> 134 </h6> 135<p> 136 The function length implements function Length from the <a href="http://www.opengeospatial.org/standards/sfa" target="_top">OGC 137 Simple Feature Specification</a>. 138 </p> 139<h6> 140<a name="geometry.reference.algorithms.length.length_1.h6"></a> 141 <span class="phrase"><a name="geometry.reference.algorithms.length.length_1.behavior"></a></span><a class="link" href="length_1.html#geometry.reference.algorithms.length.length_1.behavior">Behavior</a> 142 </h6> 143<div class="informaltable"><table class="table"> 144<colgroup> 145<col> 146<col> 147</colgroup> 148<thead><tr> 149<th> 150 <p> 151 Case 152 </p> 153 </th> 154<th> 155 <p> 156 Behavior 157 </p> 158 </th> 159</tr></thead> 160<tbody> 161<tr> 162<td> 163 <p> 164 pointlike (e.g. point) 165 </p> 166 </td> 167<td> 168 <p> 169 Returns 0 170 </p> 171 </td> 172</tr> 173<tr> 174<td> 175 <p> 176 linear (e.g. linestring) 177 </p> 178 </td> 179<td> 180 <p> 181 Returns the length 182 </p> 183 </td> 184</tr> 185<tr> 186<td> 187 <p> 188 areal (e.g. polygon) 189 </p> 190 </td> 191<td> 192 <p> 193 Returns 0 194 </p> 195 </td> 196</tr> 197</tbody> 198</table></div> 199<h6> 200<a name="geometry.reference.algorithms.length.length_1.h7"></a> 201 <span class="phrase"><a name="geometry.reference.algorithms.length.length_1.complexity"></a></span><a class="link" href="length_1.html#geometry.reference.algorithms.length.length_1.complexity">Complexity</a> 202 </h6> 203<p> 204 Linear 205 </p> 206<h6> 207<a name="geometry.reference.algorithms.length.length_1.h8"></a> 208 <span class="phrase"><a name="geometry.reference.algorithms.length.length_1.examples"></a></span><a class="link" href="length_1.html#geometry.reference.algorithms.length.length_1.examples">Examples</a> 209 </h6> 210<p> 211 The following simple example shows the calculation of the length of a 212 linestring containing three points 213 </p> 214<p> 215</p> 216<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">iostream</span><span class="special">></span> 217<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 218<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">/</span><span class="identifier">geometries</span><span class="special">/</span><span class="identifier">linestring</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 219<span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">boost</span><span class="special">/</span><span class="identifier">geometry</span><span class="special">/</span><span class="identifier">geometries</span><span class="special">/</span><span class="identifier">point_xy</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span> 220 221 222<span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span> 223<span class="special">{</span> 224 <span class="keyword">using</span> <span class="keyword">namespace</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">;</span> 225 <span class="identifier">model</span><span class="special">::</span><span class="identifier">linestring</span><span class="special"><</span><span class="identifier">model</span><span class="special">::</span><span class="identifier">d2</span><span class="special">::</span><span class="identifier">point_xy</span><span class="special"><</span><span class="keyword">double</span><span class="special">></span> <span class="special">></span> <span class="identifier">line</span><span class="special">;</span> 226 <span class="identifier">read_wkt</span><span class="special">(</span><span class="string">"linestring(0 0,1 1,4 8,3 2)"</span><span class="special">,</span> <span class="identifier">line</span><span class="special">);</span> 227 <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"linestring length is "</span> 228 <span class="special"><<</span> <span class="identifier">length</span><span class="special">(</span><span class="identifier">line</span><span class="special">)</span> 229 <span class="special"><<</span> <span class="string">" units"</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span> 230 231 <span class="keyword">return</span> <span class="number">0</span><span class="special">;</span> 232<span class="special">}</span> 233</pre> 234<p> 235 </p> 236<p> 237 Output: 238 </p> 239<pre class="programlisting">linestring length is 15.1127 units 240</pre> 241</div> 242<table xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" width="100%"><tr> 243<td align="left"></td> 244<td align="right"><div class="copyright-footer">Copyright © 2009-2019 Barend Gehrels, Bruno Lalande, Mateusz Loskot, Adam 245 Wulkiewicz, Oracle and/or its affiliates<p> 246 Distributed under the Boost Software License, Version 1.0. (See accompanying 247 file LICENSE_1_0.txt or copy at <a href="http://www.boost.org/LICENSE_1_0.txt" target="_top">http://www.boost.org/LICENSE_1_0.txt</a>) 248 </p> 249</div></td> 250</tr></table> 251<hr> 252<div class="spirit-nav"> 253<a accesskey="p" href="../length.html"><img src="../../../../../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../length.html"><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="length_2_with_strategy.html"><img src="../../../../../../../../doc/src/images/next.png" alt="Next"></a> 254</div> 255</body> 256</html> 257
