libs/geometry/doc/html/geometry/reference/algorithms/length/length_1.html

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  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="idm46186995310560"></a>
  31 Calculates 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">&lt;</span><span class="keyword">typename</span> <span class="identifier">Geometry</span><span class="special">&gt;</span>
  49 <span class="identifier">default_length_result</span><span class="special">&lt;</span><span class="identifier">Geometry</span><span class="special">&gt;::</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">&amp;</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 &amp;
  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">&lt;</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">&gt;</span></code>
 124           </p>
 125 <p>
 126             Or
 127           </p>
 128 <p>
 129             <code class="computeroutput"><span class="preprocessor">#include</span> <span class="special">&lt;</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">&gt;</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">&lt;</span><span class="identifier">iostream</span><span class="special">&gt;</span>
 217 <span class="preprocessor">#include</span> <span class="special">&lt;</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">&gt;</span>
 218 <span class="preprocessor">#include</span> <span class="special">&lt;</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">&gt;</span>
 219 <span class="preprocessor">#include</span> <span class="special">&lt;</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">&gt;</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">&lt;</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">&lt;</span><span class="keyword">double</span><span class="special">&gt;</span> <span class="special">&gt;</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">&lt;&lt;</span> <span class="string">"linestring length is "</span>
 228         <span class="special">&lt;&lt;</span> <span class="identifier">length</span><span class="special">(</span><span class="identifier">line</span><span class="special">)</span>
 229         <span class="special">&lt;&lt;</span> <span class="string">" units"</span> <span class="special">&lt;&lt;</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>
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 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>)
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