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<b>DbException</b>
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<b><pre>
#include <db_cxx.h>
<p>
class DbException {
public:
int get_errno() const;
virtual const char *what() const;
DbEnv *get_env() const;
};
</pre></b>
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<b>Description: DbException</b>
<p>This information describes the DbException class and how it is
used by the various Berkeley DB classes.</p>
<p>Most methods in the Berkeley DB classes return an int, 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 href="../../db4-devel-4.7.25/api_cxx/env_class.html#DB_CXX_NO_EXCEPTIONS">DB_CXX_NO_EXCEPTIONS</a> for the <a href="../../db4-devel-4.7.25/api_cxx/db_class.html">Db</a> and <a href="../../db4-devel-4.7.25/api_cxx/env_class.html">DbEnv</a>
constructors.</p>
<p>A DbException object contains an informational string, an errno, and a
reference to the environment from which the exception was thrown. The
errno can be obtained by using DbException::get_errno, and can be
used, in standard cases, to determine the type of the exception. The
informational string can be obtained by using DbException::what. And,
the environment can be obtained using DbException::get_env.</p>
<p>We expect in the future that this class will inherit from the standard
class exception, but certain language implementation bugs currently
prevent this on some platforms.</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,
<a href="../../db4-devel-4.7.25/api_cxx/db_get.html">Db::get</a> returns <a href="../../db4-devel-4.7.25/ref/program/errorret.html#DB_NOTFOUND">DB_NOTFOUND</a> when a requested key does
not appear in the database.</p>
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