1<?xml version="1.0" encoding="UTF-8" standalone="no"?> 2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 3<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Chapter 6. Termination</title><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /><meta name="keywords" content=" ISO C++ , library " /><link rel="home" href="../spine.html" title="The GNU C++ Library Documentation" /><link rel="up" href="support.html" title="Part II. Support" /><link rel="prev" href="dynamic_memory.html" title="Chapter 5. Dynamic Memory" /><link rel="next" href="verbose_termination.html" title="Verbose Terminate Handler" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 6. Termination</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="dynamic_memory.html">Prev</a> </td><th width="60%" align="center">Part II. 4 Support 5 6</th><td width="20%" align="right"> <a accesskey="n" href="verbose_termination.html">Next</a></td></tr></table><hr /></div><div class="chapter" title="Chapter 6. Termination"><div class="titlepage"><div><div><h2 class="title"><a id="manual.support.termination"></a>Chapter 6. Termination</h2></div></div></div><div class="toc"><p><b>Table of Contents</b></p><dl><dt><span class="sect1"><a href="termination.html#support.termination.handlers">Termination Handlers</a></span></dt><dt><span class="sect1"><a href="verbose_termination.html">Verbose Terminate Handler</a></span></dt></dl></div><div class="sect1" title="Termination Handlers"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="support.termination.handlers"></a>Termination Handlers</h2></div></div></div><p> 7 Not many changes here to <code class="filename">cstdlib</code>. You should note that the 8 <code class="function">abort()</code> function does not call the 9 destructors of automatic nor static objects, so if you're 10 depending on those to do cleanup, it isn't going to happen. 11 (The functions registered with <code class="function">atexit()</code> 12 don't get called either, so you can forget about that 13 possibility, too.) 14 </p><p> 15 The good old <code class="function">exit()</code> function can be a bit 16 funky, too, until you look closer. Basically, three points to 17 remember are: 18 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p> 19 Static objects are destroyed in reverse order of their creation. 20 </p></li><li class="listitem"><p> 21 Functions registered with <code class="function">atexit()</code> are called in 22 reverse order of registration, once per registration call. 23 (This isn't actually new.) 24 </p></li><li class="listitem"><p> 25 The previous two actions are <span class="quote">“<span class="quote">interleaved,</span>”</span> that is, 26 given this pseudocode: 27 </p><pre class="programlisting"> 28 extern "C or C++" void f1 (void); 29 extern "C or C++" void f2 (void); 30 31 static Thing obj1; 32 atexit(f1); 33 static Thing obj2; 34 atexit(f2); 35</pre><p> 36 then at a call of <code class="function">exit()</code>, 37 <code class="varname">f2</code> will be called, then 38 <code class="varname">obj2</code> will be destroyed, then 39 <code class="varname">f1</code> will be called, and finally 40 <code class="varname">obj1</code> will be destroyed. If 41 <code class="varname">f1</code> or <code class="varname">f2</code> allow an 42 exception to propagate out of them, Bad Things happen. 43 </p></li></ol></div><p> 44 Note also that <code class="function">atexit()</code> is only required to store 32 45 functions, and the compiler/library might already be using some of 46 those slots. If you think you may run out, we recommend using 47 the <code class="function">xatexit</code>/<code class="function">xexit</code> combination from <code class="literal">libiberty</code>, which has no such limit. 48 </p></div></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="dynamic_memory.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="support.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="verbose_termination.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 5. Dynamic Memory </td><td width="20%" align="center"><a accesskey="h" href="../spine.html">Home</a></td><td width="40%" align="right" valign="top"> Verbose Terminate Handler</td></tr></table></div></body></html> 49