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<div class="section">
<div class="titlepage"><div><div><h4 class="title">
<a name="geometry.reference.algorithms.num_points"></a><a class="link" href="num_points.html" title="num_points">num_points</a>
</h4></div></div></div>
<p>
<a class="indexterm" name="id895442"></a>
Calculates the number of points of a geometry.
</p>
<h6>
<a name="geometry.reference.algorithms.num_points.h0"></a>
<span><a name="geometry.reference.algorithms.num_points.description"></a></span><a class="link" href="num_points.html#geometry.reference.algorithms.num_points.description">Description</a>
</h6>
<p>
The free function num_points calculates the number of points of a geometry.
</p>
<h6>
<a name="geometry.reference.algorithms.num_points.h1"></a>
<span><a name="geometry.reference.algorithms.num_points.synopsis"></a></span><a class="link" href="num_points.html#geometry.reference.algorithms.num_points.synopsis">Synopsis</a>
</h6>
<p>
</p>
<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>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">size_t</span> <span class="identifier">num_points</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> <span class="keyword">bool</span> <span class="identifier">add_for_open</span> <span class="special">=</span> <span class="keyword">false</span><span class="special">)</span></pre>
<p>
</p>
<h6>
<a name="geometry.reference.algorithms.num_points.h2"></a>
<span><a name="geometry.reference.algorithms.num_points.parameters"></a></span><a class="link" href="num_points.html#geometry.reference.algorithms.num_points.parameters">Parameters</a>
</h6>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
Type
</p>
</th>
<th>
<p>
Concept
</p>
</th>
<th>
<p>
Name
</p>
</th>
<th>
<p>
Description
</p>
</th>
</tr></thead>
<tbody>
<tr>
<td>
<p>
Geometry const &
</p>
</td>
<td>
<p>
Any type fulfilling a Geometry Concept
</p>
</td>
<td>
<p>
geometry
</p>
</td>
<td>
<p>
A model of the specified concept
</p>
</td>
</tr>
<tr>
<td>
<p>
bool
</p>
</td>
<td>
</td>
<td>
<p>
add_for_open
</p>
</td>
<td>
<p>
add one for open geometries (i.e. polygon types which are not
closed)
</p>
</td>
</tr>
</tbody>
</table></div>
<h6>
<a name="geometry.reference.algorithms.num_points.h3"></a>
<span><a name="geometry.reference.algorithms.num_points.returns"></a></span><a class="link" href="num_points.html#geometry.reference.algorithms.num_points.returns">Returns</a>
</h6>
<p>
The calculated number of points
</p>
<h6>
<a name="geometry.reference.algorithms.num_points.h4"></a>
<span><a name="geometry.reference.algorithms.num_points.header"></a></span><a class="link" href="num_points.html#geometry.reference.algorithms.num_points.header">Header</a>
</h6>
<p>
Either
</p>
<p>
<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">geometry</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span></code>
</p>
<p>
Or
</p>
<p>
<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">num_points</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span></code>
</p>
<h6>
<a name="geometry.reference.algorithms.num_points.h5"></a>
<span><a name="geometry.reference.algorithms.num_points.conformance"></a></span><a class="link" href="num_points.html#geometry.reference.algorithms.num_points.conformance">Conformance</a>
</h6>
<p>
The function num_points implements function NumPoints from the <a href="http://www.opengeospatial.org/standards/sfa" target="_top">OGC
Simple Feature Specification</a>.
</p>
<div class="note"><table border="0" summary="Note">
<tr>
<td rowspan="2" align="center" valign="top" width="25"><img alt="[Note]" src="../../../../../../../doc/src/images/note.png"></td>
<th align="left">Note</th>
</tr>
<tr><td align="left" valign="top"><p>
num_points can be called for any geometry and not just linestrings (as
the standard describes)
</p></td></tr>
</table></div>
<h6>
<a name="geometry.reference.algorithms.num_points.h6"></a>
<span><a name="geometry.reference.algorithms.num_points.behavior"></a></span><a class="link" href="num_points.html#geometry.reference.algorithms.num_points.behavior">Behavior</a>
</h6>
<div class="informaltable"><table class="table">
<colgroup>
<col>
<col>
</colgroup>
<thead><tr>
<th>
<p>
Case
</p>
</th>
<th>
<p>
Behavior
</p>
</th>
</tr></thead>
<tbody>
<tr>
<td>
<p>
Point
</p>
</td>
<td>
<p>
Returns 1
</p>
</td>
</tr>
<tr>
<td>
<p>
Segment
</p>
</td>
<td>
<p>
Returns 2
</p>
</td>
</tr>
<tr>
<td>
<p>
Rectangle
</p>
</td>
<td>
<p>
Returns 4
</p>
</td>
</tr>
<tr>
<td>
<p>
Rangelike (linestring, ring)
</p>
</td>
<td>
<p>
Returns boost::size(geometry)
</p>
</td>
</tr>
<tr>
<td>
<p>
Other geometries
</p>
</td>
<td>
<p>
Returns the sum of the number of points of its elements
</p>
</td>
</tr>
<tr>
<td>
<p>
Open geometries
</p>
</td>
<td>
<p>
Returns the sum of the number of points of its elements, it adds
one for open (per ring) if specified
</p>
</td>
</tr>
<tr>
<td>
<p>
Closed geometries
</p>
</td>
<td>
<p>
Returns the sum of the number of points of its elements
</p>
</td>
</tr>
</tbody>
</table></div>
<h6>
<a name="geometry.reference.algorithms.num_points.h7"></a>
<span><a name="geometry.reference.algorithms.num_points.complexity"></a></span><a class="link" href="num_points.html#geometry.reference.algorithms.num_points.complexity">Complexity</a>
</h6>
<p>
Constant or Linear
</p>
<h6>
<a name="geometry.reference.algorithms.num_points.h8"></a>
<span><a name="geometry.reference.algorithms.num_points.examples"></a></span><a class="link" href="num_points.html#geometry.reference.algorithms.num_points.examples">Examples</a>
</h6>
<p>
Get the number of points in a geometry
</p>
<p>
</p>
<pre class="programlisting"><span class="preprocessor">#include</span> <span class="special"><</span><span class="identifier">iostream</span><span class="special">></span>
<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>
<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">multi</span><span class="special">/</span><span class="identifier">multi</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span>
<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>
<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">polygon</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span>
<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">multi</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">></span>
<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">io</span><span class="special">/</span><span class="identifier">wkt</span><span class="special">/</span><span class="identifier">wkt</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span>
<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">multi</span><span class="special">/</span><span class="identifier">io</span><span class="special">/</span><span class="identifier">wkt</span><span class="special">/</span><span class="identifier">wkt</span><span class="special">.</span><span class="identifier">hpp</span><span class="special">></span>
<span class="keyword">int</span> <span class="identifier">main</span><span class="special">()</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">model</span><span class="special">::</span><span class="identifier">multi_polygon</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">model</span><span class="special">::</span><span class="identifier">polygon</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">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="special">></span> <span class="identifier">mp</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">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>
<span class="identifier">std</span><span class="special">::</span><span class="identifier">cout</span> <span class="special"><<</span> <span class="string">"Number of points: "</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">num_points</span><span class="special">(</span><span class="identifier">mp</span><span class="special">)</span> <span class="special"><<</span> <span class="identifier">std</span><span class="special">::</span><span class="identifier">endl</span><span class="special">;</span>
<span class="keyword">return</span> <span class="number">0</span><span class="special">;</span>
<span class="special">}</span>
</pre>
<p>
</p>
<p>
Output:
</p>
<pre class="programlisting">Number of points: 12
</pre>
</div>
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<td align="left"></td>
<td align="right"><div class="copyright-footer">Copyright © 2009-2012 Barend
Gehrels, Bruno Lalande, Mateusz Loskot<p>
Distributed under the Boost Software License, Version 1.0. (See accompanying
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>)
</p>
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