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"><html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title>Chapter 5. Diagnostics</title><meta name="generator" content="DocBook XSL-NS Stylesheets V1.78.1" /><meta name="keywords" content="ISO C++, library" /><meta name="keywords" content="ISO C++, runtime, library" /><link rel="home" href="../index.html" title="The GNU C++ Library" /><link rel="up" href="std_contents.html" title="Part II. Standard Contents" /><link rel="prev" href="termination.html" title="Termination" /><link rel="next" href="concept_checking.html" title="Concept Checking" /></head><body><div class="navheader"><table width="100%" summary="Navigation header"><tr><th colspan="3" align="center">Chapter 5. 3 Diagnostics 4 5</th></tr><tr><td width="20%" align="left"><a accesskey="p" href="termination.html">Prev</a> </td><th width="60%" align="center">Part II. 6 Standard Contents 7 </th><td width="20%" align="right"> <a accesskey="n" href="concept_checking.html">Next</a></td></tr></table><hr /></div><div class="chapter"><div class="titlepage"><div><div><h2 class="title"><a id="std.diagnostics"></a>Chapter 5. 8 Diagnostics 9 <a id="idm270001697504" class="indexterm"></a> 10</h2></div></div></div><div class="toc"><p><strong>Table of Contents</strong></p><dl class="toc"><dt><span class="section"><a href="diagnostics.html#std.diagnostics.exceptions">Exceptions</a></span></dt><dd><dl><dt><span class="section"><a href="diagnostics.html#std.diagnostics.exceptions.api">API Reference</a></span></dt><dt><span class="section"><a href="diagnostics.html#std.diagnostics.exceptions.data">Adding Data to <code class="classname">exception</code></a></span></dt></dl></dd><dt><span class="section"><a href="concept_checking.html">Concept Checking</a></span></dt></dl></div><div class="section"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="std.diagnostics.exceptions"></a>Exceptions</h2></div></div></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="std.diagnostics.exceptions.api"></a>API Reference</h3></div></div></div><p> 11 All exception objects are defined in one of the standard header 12 files: <code class="filename">exception</code>, 13 <code class="filename">stdexcept</code>, <code class="filename">new</code>, and 14 <code class="filename">typeinfo</code>. 15 </p><p> 16 The base exception object is <code class="classname">exception</code>, 17 located in <code class="filename">exception</code>. This object has no 18 <code class="classname">string</code> member. 19 </p><p> 20 Derived from this are several classes that may have a 21 <code class="classname">string</code> member: a full hierarchy can be 22 found in the source documentation. 23 </p><p> 24 Full API details. 25 </p></div><div class="section"><div class="titlepage"><div><div><h3 class="title"><a id="std.diagnostics.exceptions.data"></a>Adding Data to <code class="classname">exception</code></h3></div></div></div><p> 26 The standard exception classes carry with them a single string as 27 data (usually describing what went wrong or where the 'throw' took 28 place). It's good to remember that you can add your own data to 29 these exceptions when extending the hierarchy: 30 </p><pre class="programlisting"> 31 struct My_Exception : public std::runtime_error 32 { 33 public: 34 My_Exception (const string& whatarg) 35 : std::runtime_error(whatarg), e(errno), id(GetDataBaseID()) { } 36 int errno_at_time_of_throw() const { return e; } 37 DBID id_of_thing_that_threw() const { return id; } 38 protected: 39 int e; 40 DBID id; // some user-defined type 41 }; 42 </pre></div></div></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="std_contents.html">Up</a></td><td width="40%" align="right"> <a accesskey="n" href="concept_checking.html">Next</a></td></tr><tr><td width="40%" align="left" valign="top">Termination </td><td width="20%" align="center"><a accesskey="h" href="../index.html">Home</a></td><td width="40%" align="right" valign="top"> Concept Checking</td></tr></table></div></body></html>