<?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. The DbException Class</title> <link rel="stylesheet" href="apiReference.css" type="text/css" /> <meta name="generator" content="DocBook XSL Stylesheets V1.73.2" /> <link rel="start" href="index.html" title="Berkeley DB C++ API Reference" /> <link rel="up" href="index.html" title="Berkeley DB C++ API Reference" /> <link rel="prev" href="envversion.html" title="DbEnv::version()" /> <link rel="next" href="dbdeadlock.html" title="DbDeadlockException" /> </head> <body> <div xmlns="" class="navheader"> <div class="libver"> <p>Library Version 11.2.5.3</p> </div> <table width="100%" summary="Navigation header"> <tr> <th colspan="3" align="center">Chapter 6. The DbException Class</th> </tr> <tr> <td width="20%" align="left"><a accesskey="p" href="envversion.html">Prev</a> </td> <th width="60%" align="center"> </th> <td width="20%" align="right"> <a accesskey="n" href="dbdeadlock.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="dbexception"></a>Chapter 6. The DbException Class</h2> </div> </div> </div> <pre class="programlisting">#include <db_cxx.h> class DbException { public: int get_errno() const; virtual const char *what() const; DbEnv *get_env() const; }; </pre> <p> This information describes the <code class="classname">DbException</code> class and how it is used by the various Berkeley DB classes. </p> <p> Most methods in the Berkeley DB classes return an <code class="literal">int</code>, but also throw an exception. This allows for two different error behaviors. By default, the Berkeley DB C++ API is configured to throw an exception whenever a serious error occurs. This generally allows for cleaner logic for transaction processing because a try block can surround a single transaction. Alternatively, Berkeley DB can be configured to not throw exceptions, and instead have the individual function return an error code, by setting the <a class="link" href="envcreate.html#env_DB_CXX_NO_EXCEPTIONS">DB_CXX_NO_EXCEPTIONS</a> for the <a class="xref" href="dbcreate.html" title="Db">Db</a> and <a class="xref" href="envcreate.html" title="DbEnv">DbEnv</a> constructors. </p> <p> A <code class="classname">DbException</code> object contains an informational string, an <code class="literal">errno</code>, and a reference to the environment from which the exception was thrown. The <code class="literal">errno</code> can be obtained by using the <code class="methodname">DbException::get_errno()</code> method, and can be used, in standard cases, to determine the type of the exception. The informational string can be obtained by using the <code class="methodname">DbException::what()</code>. And, the environment can be obtained using the <code class="methodname">DbException::get_env()</code> method. </p> <p> Where available, this class inherits from the standard class exception. </p> <p> Some methods may return non-zero values without issuing an exception. This occurs in situations that are not normally considered an error, but when some informational status is returned. For example, the <a class="xref" href="dbget.html" title="Db::get()">Db::get()</a> method returns <a href="../../programmer_reference/program_errorret.html#program_errorret.DB_NOTFOUND" class="olink">DB_NOTFOUND</a> when a requested key does not appear in the database. </p> <div class="sect1" lang="en" xml:lang="en"> <div class="titlepage"> <div> <div> <h2 class="title" style="clear: both"><a id="exceptionlist"></a>DB C++ Exceptions</h2> </div> </div> </div> <div class="navtable"> <table border="1" width="80%"> <thead> <tr> <th>DB C++ Exceptions</th> <th>Description</th> </tr> </thead> <tbody> <tr> <td> <a class="xref" href="dbdeadlock.html" title="DbDeadlockException">DbDeadlockException</a> </td> <td>Exception class for deadlocks</td> </tr> <tr> <td> <a class="xref" href="dblocknotgranted.html" title="DbLockNotGrantedException">DbLockNotGrantedException</a> </td> <td>Exception class for lock request failures</td> </tr> <tr> <td> <a class="xref" href="dbmemory.html" title="DbMemoryException">DbMemoryException</a> </td> <td>Exception class for insufficient memory</td> </tr> <tr> <td> <a class="xref" href="dbrephandledead.html" title="DbRepHandleDeadException">DbRepHandleDeadException</a> </td> <td>Exception class for database and cursor handles that are invalidated in a replicated application. </td> </tr> <tr> <td> <a class="xref" href="dbrunrecovery.html" title="DbRunRecoveryException">DbRunRecoveryException</a> </td> <td>Exception class for failures requiring recovery</td> </tr> </tbody> </table> </div> </div> </div> <div class="navfooter"> <hr /> <table width="100%" summary="Navigation footer"> <tr> <td width="40%" align="left"><a accesskey="p" href="envversion.html">Prev</a> </td> <td width="20%" align="center"> </td> <td width="40%" align="right"> <a accesskey="n" href="dbdeadlock.html">Next</a></td> </tr> <tr> <td width="40%" align="left" valign="top">DbEnv::version() </td> <td width="20%" align="center"> <a accesskey="h" href="index.html">Home</a> </td> <td width="40%" align="right" valign="top"> DbDeadlockException</td> </tr> </table> </div> </body> </html>