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<h2 class="title" style="clear: both"><a id="dbset_errfile"></a>Db::set_errfile()</h2>
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<pre class="programlisting">#include <db_cxx.h>
void Db::set_errfile(FILE *errfile); </pre>
<p>
When an error occurs in the Berkeley DB library,
<span>
an exception is thrown
</span>
or an error return value is returned by the interface. In some cases,
however, the <span class="bold"><strong>errno</strong></span> value may be
insufficient to completely describe the cause of the error, especially
during initial application debugging.
</p>
<p>
The <a class="xref" href="envset_errfile.html" title="DbEnv::set_errfile()">DbEnv::set_errfile()</a> and
<code class="methodname">Db::set_errfile()</code> methods are used to enhance the mechanism for
reporting error messages to the application by setting a C library
FILE * to be used for displaying additional Berkeley DB error
messages. In some cases, when an error occurs, Berkeley DB will
output an additional error message to the specified file reference.
</p>
<p>
Alternatively, you can use the
<span>
<a class="xref" href="envset_error_stream.html" title="DbEnv::set_error_stream()">DbEnv::set_error_stream()</a>
and
<a class="xref" href="dbset_error_stream.html" title="Db::set_error_stream()">Db::set_error_stream()</a>
methods to display the additional messages via an output stream, or the
</span>
<a class="xref" href="envset_errcall.html" title="DbEnv::set_errcall()">DbEnv::set_errcall()</a> or
<a class="xref" href="dbset_errcall.html" title="Db::set_errcall()">Db::set_errcall()</a>
methods to capture the additional error information in a way that does
not use C library FILE *'s.
<span>You should not mix these approaches.</span>
</p>
<p>
The error message will consist of the prefix string and a colon
("<span class="bold"><strong>:</strong></span>") (if a prefix string was
previously specified using
<a class="xref" href="dbset_errpfx.html" title="Db::set_errpfx()">Db::set_errpfx()</a> or
<a class="xref" href="envset_errpfx.html" title="DbEnv::set_errpfx()">DbEnv::set_errpfx()</a> ), an
error string, and a trailing <newline> character.
</p>
<p>
The default configuration when applications first create
<a class="link" href="db.html" title="Chapter 2. The Db Handle">Db</a> or
<a class="link" href="env.html" title="Chapter 5. The DbEnv Handle">DbEnv</a> handles is as if the
<a class="xref" href="envset_errfile.html" title="DbEnv::set_errfile()">DbEnv::set_errfile()</a> or
<code class="methodname">Db::set_errfile()</code> methods were called with the standard error output
(stderr) specified as the FILE * argument. Applications wanting no
output at all can turn off this default configuration by calling the
<a class="xref" href="envset_errfile.html" title="DbEnv::set_errfile()">DbEnv::set_errfile()</a> or
<code class="methodname">Db::set_errfile()</code> methods with NULL as the FILE * argument.
Additionally, explicitly configuring the error output channel using
any of the following methods will also turn off this default output for the application:
</p>
<div class="itemizedlist">
<ul type="disc">
<li>
<p>
<code class="methodname">Db::set_errfile()</code>
</p>
</li>
<li>
<p>
<a class="xref" href="envset_errfile.html" title="DbEnv::set_errfile()">DbEnv::set_errfile()</a>
</p>
</li>
<li>
<p>
<a class="xref" href="envset_errcall.html" title="DbEnv::set_errcall()">DbEnv::set_errcall()</a>
</p>
</li>
<li>
<p>
<a class="xref" href="dbset_errcall.html" title="Db::set_errcall()">Db::set_errcall()</a>
</p>
</li>
<li>
<p>
<a class="xref" href="envset_error_stream.html" title="DbEnv::set_error_stream()">DbEnv::set_error_stream()</a>
</p>
</li>
<li>
<p>
<a class="xref" href="dbset_error_stream.html" title="Db::set_error_stream()">Db::set_error_stream()</a>
</p>
</li>
</ul>
</div>
<p>
This error logging enhancement does not slow performance or
significantly increase application size, and may be run during normal
operation as well as during application debugging.
</p>
<p>
For <a class="link" href="db.html" title="Chapter 2. The Db Handle">Db</a> handles opened
inside of Berkeley DB environments, calling the
<code class="methodname">Db::set_errfile()</code>
method affects the entire environment and is equivalent to calling the
<a class="xref" href="envset_errfile.html" title="DbEnv::set_errfile()">DbEnv::set_errfile()</a>
method.
</p>
<p>
When used on a database that was <span class="emphasis"><em>not</em></span> opened in
an environment, the <code class="methodname">Db::set_errfile()</code>
method configures operations performed using the specified
<a class="link" href="db.html" title="Chapter 2. The Db Handle">Db</a> handle, not all operations
performed on the underlying database.
</p>
<p>
The <code class="methodname">Db::set_errfile()</code> method may be called at any time during the
life of the application.
</p>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp1381032"></a>Parameters</h3>
</div>
</div>
</div>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="idp1360312"></a>errfile</h4>
</div>
</div>
</div>
<p>
The <span class="bold"><strong>errfile</strong></span> parameter is a C library
<code class="literal">FILE *</code> to be used for displaying additional Berkeley DB error
information.
</p>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="idp1726384"></a>Class</h3>
</div>
</div>
</div>
<p>
<a class="link" href="db.html" title="Chapter 2. The Db Handle">Db</a>
</p>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
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<h3 class="title"><a id="idp2025584"></a>See Also</h3>
</div>
</div>
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<p>
<a class="xref" href="db.html#dblist" title="Database and Related Methods">Database and Related Methods</a>
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