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<?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>Verbose Terminate Handler</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="termination.html" title="Chapter 6. Termination" /><link rel="prev" href="termination.html" title="Chapter 6. Termination" /><link rel="next" href="diagnostics.html" title="Part III. Diagnostics" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Verbose Terminate Handler</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="termination.html">Prev</a> </td><th width="60%" align="center">Chapter 6. Termination</th><td width="20%" align="right"> <a accesskey="n" href="diagnostics.html">Next</a></td></tr></table><hr /></div><div class="sect1" title="Verbose Terminate Handler"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="support.termination.verbose"></a>Verbose Terminate Handler</h2></div></div></div><p> If you are having difficulty with uncaught exceptions and want a little bit of help debugging the causes of the core dumps, you can make use of a GNU extension, the verbose terminate handler. </p><pre class="programlisting"> #include <exception> int main() { std::set_terminate(__gnu_cxx::__verbose_terminate_handler); ... throw <em class="replaceable"><code>anything</code></em>; } </pre><p> The <code class="function">__verbose_terminate_handler</code> function obtains the name of the current exception, attempts to demangle it, and prints it to stderr. If the exception is derived from <code class="classname">exception</code> then the output from <code class="function">what()</code> will be included. </p><p> Any replacement termination function is required to kill the program without returning; this one calls abort. </p><p> For example: </p><pre class="programlisting"> #include <exception> #include <stdexcept> struct argument_error : public std::runtime_error { argument_error(const std::string& s): std::runtime_error(s) { } }; int main(int argc) { std::set_terminate(__gnu_cxx::__verbose_terminate_handler); if (argc > 5) throw argument_error(<span class="quote">“<span class="quote">argc is greater than 5!</span>”</span>); else throw argc; } </pre><p> With the verbose terminate handler active, this gives: </p><pre class="screen"> <code class="computeroutput"> % ./a.out terminate called after throwing a `int' Aborted % ./a.out f f f f f f f f f f f terminate called after throwing an instance of `argument_error' what(): argc is greater than 5! Aborted </code> </pre><p> The 'Aborted' line comes from the call to <code class="function">abort()</code>, of course. </p><p> This is the default termination handler; nothing need be done to use it. To go back to the previous <span class="quote">“<span class="quote">silent death</span>”</span> method, simply include <code class="filename">exception</code> and <code class="filename">cstdlib</code>, and call </p><pre class="programlisting"> std::set_terminate(std::abort); </pre><p> After this, all calls to <code class="function">terminate</code> will use <code class="function">abort</code> as the terminate handler. </p><p> Note: the verbose terminate handler will attempt to write to stderr. If your application closes stderr or redirects it to an inappropriate location, <code class="function">__verbose_terminate_handler</code> will behave in an unspecified manner. </p></div><div class="navfooter"><hr /><table width="100%" summary="Navigation footer"><tr><td width="40%" align="left"><a accesskey="p" href="termination.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="termination.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="diagnostics.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Chapter 6. Termination </td><td width="20%" align="center"><a accesskey="h" href="../spine.html">Home</a></td><td width="40%" align="right" valign="top"> Part III. Diagnostics </td></tr></table></div></body></html>
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