<!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>Function template get_mpi_datatype</title> <link rel="stylesheet" href="../../../../doc/src/boostbook.css" type="text/css"> <meta name="generator" content="DocBook XSL Stylesheets V1.78.1"> <link rel="home" href="../../index.html" title="The Boost C++ Libraries BoostBook Documentation Subset"> <link rel="up" href="../../mpi/reference.html#header.boost.mpi.datatype_hpp" title="Header <boost/mpi/datatype.hpp>"> <link rel="prev" href="is_mpi_logical_datatype.html" title="Struct template is_mpi_logical_datatype"> <link rel="next" href="../../BOOST_IS_MPI_DATATYPE.html" title="Macro BOOST_IS_MPI_DATATYPE"> </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="is_mpi_logical_datatype.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../../mpi/reference.html#header.boost.mpi.datatype_hpp"><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="../../BOOST_IS_MPI_DATATYPE.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> </div> <div class="refentry"> <a name="boost.mpi.get_mpi__idm45507086028144"></a><div class="titlepage"></div> <div class="refnamediv"> <h2><span class="refentrytitle">Function template get_mpi_datatype</span></h2> <p>boost::mpi::get_mpi_datatype — Returns an MPI data type for a C++ type. </p> </div> <h2 xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv-title">Synopsis</h2> <div xmlns:rev="http://www.cs.rpi.edu/~gregod/boost/tools/doc/revision" class="refsynopsisdiv"><pre class="synopsis"><span class="comment">// In header: <<a class="link" href="../../mpi/reference.html#header.boost.mpi.datatype_hpp" title="Header <boost/mpi/datatype.hpp>">boost/mpi/datatype.hpp</a>> </span> <span class="keyword">template</span><span class="special"><</span><span class="keyword">typename</span> T<span class="special">></span> <span class="identifier">MPI_Datatype</span> <span class="identifier">get_mpi_datatype</span><span class="special">(</span><span class="keyword">const</span> <span class="identifier">T</span> <span class="special">&</span> x<span class="special">)</span><span class="special">;</span></pre></div> <div class="refsect1"> <a name="idm45555222249488"></a><h2>Description</h2> <p>The function creates an MPI data type for the given object <code class="computeroutput">x</code>. The first time it is called for a class <code class="computeroutput">T</code>, the MPI data type is created and cached. Subsequent calls for objects of the same type <code class="computeroutput">T</code> return the cached MPI data type. The type <code class="computeroutput">T</code> must allow creation of an MPI data type. That is, it must be Serializable and <code class="computeroutput">is_mpi_datatype<T></code> must derive <code class="computeroutput">mpl::true_</code>.</p> <p>For fundamental MPI types, a copy of the MPI data type of the MPI library is returned.</p> <p>Note that since the data types are cached, the caller should never call <code class="computeroutput">MPI_Type_free()</code> for the MPI data type returned by this call.</p> <p> </p> <div class="variablelist"><table border="0" class="variablelist compact"> <colgroup> <col align="left" valign="top"> <col> </colgroup> <tbody> <tr> <td><p><span class="term">Parameters:</span></p></td> <td><div class="variablelist"><table border="0" class="variablelist compact"> <colgroup> <col align="left" valign="top"> <col> </colgroup> <tbody><tr> <td><p><span class="term"><code class="computeroutput">x</code></span></p></td> <td><p>for an optimized call, a constructed object of the type should be passed; otherwise, an object will be default-constructed.</p></td> </tr></tbody> </table></div></td> </tr> <tr> <td><p><span class="term">Returns:</span></p></td> <td><p>The MPI data type corresponding to type <code class="computeroutput">T</code>. </p></td> </tr> </tbody> </table></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 © 2005-2007 Douglas Gregor, Matthias Troyer, Trustees of Indiana University<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> </div></td> </tr></table> <hr> <div class="spirit-nav"> <a accesskey="p" href="is_mpi_logical_datatype.html"><img src="../../../../doc/src/images/prev.png" alt="Prev"></a><a accesskey="u" href="../../mpi/reference.html#header.boost.mpi.datatype_hpp"><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="../../BOOST_IS_MPI_DATATYPE.html"><img src="../../../../doc/src/images/next.png" alt="Next"></a> </div> </body> </html>