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| <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 V1.73.2" /><meta name="keywords" content=" ISO C++ , library " /><link rel="start" href="../spine.html" title="The GNU C++ Library Documentation" /><link rel="up" href="bk01pt02ch06.html" title="Chapter 6. Termination" /><link rel="prev" href="bk01pt02ch06.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="bk01pt02ch06.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" lang="en" xml:lang="en"><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">argc is greater than 5!</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">silent death</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="bk01pt02ch06.html">Prev</a> </td><td width="20%" align="center"><a accesskey="u" href="bk01pt02ch06.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> |
