<?xml version="1.0" encoding="UTF-8" standalone="no"?> <!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> <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 V1.74.0" /><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. Support </th><td width="20%" align="right"> <a accesskey="n" href="verbose_termination.html">Next</a></td></tr></table><hr /></div><div class="chapter" lang="en" xml:lang="en"><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" lang="en" xml:lang="en"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="support.termination.handlers"></a>Termination Handlers</h2></div></div></div><p> Not many changes here to <code class="filename">cstdlib</code>. You should note that the <code class="function">abort()</code> function does not call the destructors of automatic nor static objects, so if you're depending on those to do cleanup, it isn't going to happen. (The functions registered with <code class="function">atexit()</code> don't get called either, so you can forget about that possibility, too.) </p><p> The good old <code class="function">exit()</code> function can be a bit funky, too, until you look closer. Basically, three points to remember are: </p><div class="orderedlist"><ol type="1"><li><p> Static objects are destroyed in reverse order of their creation. </p></li><li><p> Functions registered with <code class="function">atexit()</code> are called in reverse order of registration, once per registration call. (This isn't actually new.) </p></li><li><p> The previous two actions are “<span class="quote">interleaved,</span>” that is, given this pseudocode: </p><pre class="programlisting"> extern "C or C++" void f1 (void); extern "C or C++" void f2 (void); static Thing obj1; atexit(f1); static Thing obj2; atexit(f2); </pre><p> then at a call of <code class="function">exit()</code>, <code class="varname">f2</code> will be called, then <code class="varname">obj2</code> will be destroyed, then <code class="varname">f1</code> will be called, and finally <code class="varname">obj1</code> will be destroyed. If <code class="varname">f1</code> or <code class="varname">f2</code> allow an exception to propagate out of them, Bad Things happen. </p></li></ol></div><p> Note also that <code class="function">atexit()</code> is only required to store 32 functions, and the compiler/library might already be using some of those slots. If you think you may run out, we recommend using the <code class="function">xatexit</code>/<code class="function">xexit</code> combination from <code class="literal">libiberty</code>, which has no such limit. </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>