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3  Extensions
4  
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6    The <code class="filename">&lt;functional&gt;</code> header
7    contains many additional functors
8    and helper functions, extending section 20.3.  They are
9    implemented in the file stl_function.h:
10  </p><div class="itemizedlist"><ul class="itemizedlist" style="list-style-type: disc; "><li class="listitem"><p><code class="code">identity_element</code> for addition and multiplication.
11  </p></li><li class="listitem"><p>The functor <code class="code">identity</code>, whose <code class="code">operator()</code>
12      returns the argument unchanged.
13  </p></li><li class="listitem"><p>Composition functors <code class="code">unary_function</code> and
14      <code class="code">binary_function</code>, and their helpers <code class="code">compose1</code>
15      and <code class="code">compose2</code>.
16    </p></li><li class="listitem"><p><code class="code">select1st</code> and <code class="code">select2nd</code>, to strip pairs.
17  </p></li><li class="listitem"><p><code class="code">project1st</code> and <code class="code">project2nd</code>. </p></li><li class="listitem"><p>A set of functors/functions which always return the same result.  They
18      are <code class="code">constant_void_fun</code>, <code class="code">constant_binary_fun</code>,
19      <code class="code">constant_unary_fun</code>, <code class="code">constant0</code>,
20      <code class="code">constant1</code>, and <code class="code">constant2</code>. </p></li><li class="listitem"><p>The class <code class="code">subtractive_rng</code>. </p></li><li class="listitem"><p>mem_fun adaptor helpers <code class="code">mem_fun1</code> and
21      <code class="code">mem_fun1_ref</code> are provided for backwards compatibility. </p></li></ul></div><p>
22  20.4.1 can use several different allocators; they are described on the
23   main extensions page.
24</p><p>
25  20.4.3 is extended with a special version of
26  <code class="code">get_temporary_buffer</code> taking a second argument.  The
27  argument is a pointer, which is ignored, but can be used to specify
28  the template type (instead of using explicit function template
29  arguments like the standard version does).  That is, in addition to
30</p><pre class="programlisting">
31get_temporary_buffer&lt;int&gt;(5);
32</pre><p>
33you can also use
34</p><pre class="programlisting">
35get_temporary_buffer(5, (int*)0);
36</pre><p>
37  A class <code class="code">temporary_buffer</code> is given in stl_tempbuf.h.
38</p><p>
39  The specialized algorithms of section 20.4.4 are extended with
40  <code class="code">uninitialized_copy_n</code>.
41</p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="ext_sgi.html">Prev</a>��</td><td width="20%" align="center"><a accesskey="u" href="extensions.html">Up</a></td><td width="40%" align="right">��<a accesskey="n" href="ext_algorithms.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Deprecated��</td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top">��Chapter��24.��Algorithms</td></tr></table></div></body></html>