117 lines
4.2 KiB
HTML
117 lines
4.2 KiB
HTML
<?xml version="1.0" encoding="UTF-8" standalone="no"?>
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<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
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<html xmlns="http://www.w3.org/1999/xhtml">
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<head>
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<meta http-equiv="Content-Type" content="text/html; charset=UTF-8" />
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<title>Exception Handling</title>
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<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
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<meta name="generator" content="DocBook XSL Stylesheets V1.62.4" />
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<link rel="home" href="index.html" title="Getting Started with Berkeley DB" />
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<link rel="up" href="introduction.html" title="Chapter 1. Introduction to Berkeley DB " />
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<link rel="previous" href="environments.html" title="Environments" />
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<link rel="next" href="returns.html" title="Error Returns" />
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</head>
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<body>
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<div class="navheader">
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<table width="100%" summary="Navigation header">
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<tr>
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<th colspan="3" align="center">Exception Handling</th>
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</tr>
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<tr>
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<td width="20%" align="left"><a accesskey="p" href="environments.html">Prev</a> </td>
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<th width="60%" align="center">Chapter 1. Introduction to Berkeley DB </th>
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<td width="20%" align="right"> <a accesskey="n" href="returns.html">Next</a></td>
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</tr>
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</table>
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<hr />
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</div>
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<div class="sect1" lang="en" xml:lang="en">
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<div class="titlepage">
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<div>
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<div>
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<h2 class="title" style="clear: both"><a id="coreExceptions"></a>Exception Handling</h2>
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</div>
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</div>
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<div></div>
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</div>
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<p>
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Before continuing, it is useful to spend a few moments on exception
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handling in DB with the
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<span>C++ API</span>.
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</p>
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<p>
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<span>By default, most</span>
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DB methods throw
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<tt class="classname">DbException</tt>
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in the event of a serious error.
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<span>
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However, be aware that
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<tt class="classname">DbException</tt> does not inherit from
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<tt class="classname">std::exception</tt> so your <tt class="literal">try</tt>
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blocks should catch both types of exceptions. For example:
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</span>
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</p>
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<a id="cxx_intro1"></a>
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<pre class="programlisting">#include <db_cxx.h>
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...
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try
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{
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// DB and other code goes here
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}
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catch(DbException &e)
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{
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// DB error handling goes here
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}
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catch(std::exception &e)
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{
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// All other error handling goes here
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} </pre>
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<p>
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You can obtain the DB error number for a
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<tt class="classname">DbException</tt>
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by using
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<span>
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<tt class="methodname">DbException::get_errno()</tt>.
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You can also obtain the informational message associated with that error
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number using <tt class="methodname">DbException::what()</tt>.
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</span>
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</p>
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<p>
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If for some reason you do not want to manage
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<tt class="classname">DbException</tt> objects in your
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<tt class="literal">try</tt> blocks, you can configure DB to suppress them
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by setting <tt class="literal">DB_CXX_NO_EXCEPTIONS</tt> for your database and
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environment handles. In this event, you must manage your DB error
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conditions using the integer value returned by all DB methods. Be
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aware that this manual assumes that you want to manage your error
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conditions using <tt class="classname">DbException</tt> objects.
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</p>
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</div>
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<div class="navfooter">
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<hr />
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<table width="100%" summary="Navigation footer">
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<tr>
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<td width="40%" align="left"><a accesskey="p" href="environments.html">Prev</a> </td>
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<td width="20%" align="center">
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<a accesskey="u" href="introduction.html">Up</a>
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</td>
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<td width="40%" align="right"> <a accesskey="n" href="returns.html">Next</a></td>
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</tr>
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<tr>
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<td width="40%" align="left" valign="top">Environments </td>
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<td width="20%" align="center">
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<a accesskey="h" href="index.html">Home</a>
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</td>
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<td width="40%" align="right" valign="top"> Error Returns</td>
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</tr>
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</table>
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</div>
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</body>
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</html>
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