libs/geometry/doc/html/geometry/reference/algorithms/num_geometries.html

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  25 <div class="section">
  26 <div class="titlepage"><div><div><h4 class="title">
  27 <a name="geometry.reference.algorithms.num_geometries"></a><a class="link" href="num_geometries.html" title="num_geometries">num_geometries</a>
  28 </h4></div></div></div>
  29 <p>
  30           <a class="indexterm" name="idm46186993978624"></a>
  31 Calculates the number of geometries of a geometry.
  32         </p>
  33 <h6>
  34 <a name="geometry.reference.algorithms.num_geometries.h0"></a>
  35           <span class="phrase"><a name="geometry.reference.algorithms.num_geometries.description"></a></span><a class="link" href="num_geometries.html#geometry.reference.algorithms.num_geometries.description">Description</a>
  36         </h6>
  37 <p>
  38           The free function num_geometries calculates the number of geometries of
  39           a geometry.
  40         </p>
  41 <h6>
  42 <a name="geometry.reference.algorithms.num_geometries.h1"></a>
  43           <span class="phrase"><a name="geometry.reference.algorithms.num_geometries.synopsis"></a></span><a class="link" href="num_geometries.html#geometry.reference.algorithms.num_geometries.synopsis">Synopsis</a>
  44         </h6>
  45 <p>
  46 </p>
  47 <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>
  48 <span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">num_geometries</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>
  49 <p>
  50         </p>
  51 <h6>
  52 <a name="geometry.reference.algorithms.num_geometries.h2"></a>
  53           <span class="phrase"><a name="geometry.reference.algorithms.num_geometries.parameters"></a></span><a class="link" href="num_geometries.html#geometry.reference.algorithms.num_geometries.parameters">Parameters</a>
  54         </h6>
  55 <div class="informaltable"><table class="table">
  56 <colgroup>
  57 <col>
  58 <col>
  59 <col>
  60 <col>
  61 </colgroup>
  62 <thead><tr>
  63 <th>
  64                   <p>
  65                     Type
  66                   </p>
  67                 </th>
  68 <th>
  69                   <p>
  70                     Concept
  71                   </p>
  72                 </th>
  73 <th>
  74                   <p>
  75                     Name
  76                   </p>
  77                 </th>
  78 <th>
  79                   <p>
  80                     Description
  81                   </p>
  82                 </th>
  83 </tr></thead>
  84 <tbody><tr>
  85 <td>
  86                   <p>
  87                     Geometry const &amp;
  88                   </p>
  89                 </td>
  90 <td>
  91                   <p>
  92                     Any type fulfilling a Geometry Concept
  93                   </p>
  94                 </td>
  95 <td>
  96                   <p>
  97                     geometry
  98                   </p>
  99                 </td>
 100 <td>
 101                   <p>
 102                     A model of the specified concept
 103                   </p>
 104                 </td>
 105 </tr></tbody>
 106 </table></div>
 107 <h6>
 108 <a name="geometry.reference.algorithms.num_geometries.h3"></a>
 109           <span class="phrase"><a name="geometry.reference.algorithms.num_geometries.returns"></a></span><a class="link" href="num_geometries.html#geometry.reference.algorithms.num_geometries.returns">Returns</a>
 110         </h6>
 111 <p>
 112           The calculated number of geometries
 113         </p>
 114 <h6>
 115 <a name="geometry.reference.algorithms.num_geometries.h4"></a>
 116           <span class="phrase"><a name="geometry.reference.algorithms.num_geometries.header"></a></span><a class="link" href="num_geometries.html#geometry.reference.algorithms.num_geometries.header">Header</a>
 117         </h6>
 118 <p>
 119           Either
 120         </p>
 121 <p>
 122           <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>
 123         </p>
 124 <p>
 125           Or
 126         </p>
 127 <p>
 128           <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">num_geometries</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span></code>
 129         </p>
 130 <h6>
 131 <a name="geometry.reference.algorithms.num_geometries.h5"></a>
 132           <span class="phrase"><a name="geometry.reference.algorithms.num_geometries.conformance"></a></span><a class="link" href="num_geometries.html#geometry.reference.algorithms.num_geometries.conformance">Conformance</a>
 133         </h6>
 134 <p>
 135           The function num_geometries implements function NumGeometries from the
 136           <a href="http://www.opengeospatial.org/standards/sfa" target="_top">OGC Simple Feature
 137           Specification</a>.
 138         </p>
 139 <h6>
 140 <a name="geometry.reference.algorithms.num_geometries.h6"></a>
 141           <span class="phrase"><a name="geometry.reference.algorithms.num_geometries.behavior"></a></span><a class="link" href="num_geometries.html#geometry.reference.algorithms.num_geometries.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                     single (e.g. point, polygon)
 165                   </p>
 166                 </td>
 167 <td>
 168                   <p>
 169                     Returns 1
 170                   </p>
 171                 </td>
 172 </tr>
 173 <tr>
 174 <td>
 175                   <p>
 176                     multiple (e.g. multi_point, multi_polygon)
 177                   </p>
 178                 </td>
 179 <td>
 180                   <p>
 181                     Returns boost::size(geometry); the input is considered as a range
 182                   </p>
 183                 </td>
 184 </tr>
 185 </tbody>
 186 </table></div>
 187 <h6>
 188 <a name="geometry.reference.algorithms.num_geometries.h7"></a>
 189           <span class="phrase"><a name="geometry.reference.algorithms.num_geometries.complexity"></a></span><a class="link" href="num_geometries.html#geometry.reference.algorithms.num_geometries.complexity">Complexity</a>
 190         </h6>
 191 <p>
 192           Constant
 193         </p>
 194 <h6>
 195 <a name="geometry.reference.algorithms.num_geometries.h8"></a>
 196           <span class="phrase"><a name="geometry.reference.algorithms.num_geometries.examples"></a></span><a class="link" href="num_geometries.html#geometry.reference.algorithms.num_geometries.examples">Examples</a>
 197         </h6>
 198 <p>
 199           Get the number of geometries making up a multi-geometry
 200         </p>
 201 <p>
 202 </p>
 203 <pre class="programlisting"><span class="preprocessor">#include</span> <span class="special">&lt;</span><span class="identifier">iostream</span><span class="special">&gt;</span>
 204
 205 <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>
 206 <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>
 207 <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">polygon</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
 208 <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">multi_polygon</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">&gt;</span>
 209
 210
 211 <span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</span>
 212 <span class="special">{</span>
 213     <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">model</span><span class="special">::</span><span class="identifier">multi_polygon</span>
 214         <span class="special">&lt;</span>
 215             <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">model</span><span class="special">::</span><span class="identifier">polygon</span>
 216                 <span class="special">&lt;</span>
 217                     <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</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">&lt;</span><span class="keyword">double</span><span class="special">&gt;</span>
 218                 <span class="special">&gt;</span>
 219         <span class="special">&gt;</span> <span class="identifier">mp</span><span class="special">;</span>
 220     <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">read_wkt</span><span class="special">(</span><span class="string">"MULTIPOLYGON(((0 0,0 10,10 0,0 0),(1 1,1 9,9 1,1 1)),((10 10,10 7,7 10,10 10)))"</span><span class="special">,</span> <span class="identifier">mp</span><span class="special">);</span>
 221     <span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special">&lt;&lt;</span> <span class="string">"Number of geometries: "</span> <span class="special">&lt;&lt;</span> <span class="identifier">boost</span><span class="special">::</span><span class="identifier">geometry</span><span class="special">::</span><span class="identifier">num_geometries</span><span class="special">(</span><span class="identifier">mp</span><span class="special">)</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>
 222
 223     <span class="keyword">return</span> <span class="number">0</span><span class="special">;</span>
 224 <span class="special">}</span>
 225 </pre>
 226 <p>
 227         </p>
 228 <p>
 229           Output:
 230         </p>
 231 <pre class="programlisting">Number of geometries: 2
 232 </pre>
 233 </div>
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 235 <td align="left"></td>
 236 <td align="right"><div class="copyright-footer">Copyright &#169; 2009-2019 Barend Gehrels, Bruno Lalande, Mateusz Loskot, Adam
 237       Wulkiewicz, Oracle and/or its affiliates<p>
 238         Distributed under the Boost Software License, Version 1.0. (See accompanying
 239         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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