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<h2 class="title" style="clear: both"><a id="dbset_append_recno"></a>DB->set_append_recno()</h2>
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<pre class="programlisting">#include <db.h>
int
DB->set_append_recno(DB *,
int (*db_append_recno_fcn)(DB *dbp, DBT *data, db_recno_t recno)); </pre>
<p>
When using the <a class="link" href="dbput.html#dbput_DB_APPEND">DB_APPEND</a>
option of the <a class="xref" href="dbput.html" title="DB->put()">DB->put()</a> method, it may be
useful to modify the stored data based on the generated key. If a
callback function is specified using the
<code class="methodname">DB->set_append_recno()</code>
method, it will be called after the record number has been selected,
but before the data has been stored.
</p>
<p>
The <code class="methodname">DB->set_append_recno()</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_append_recno()</code> method may not be called after the
<a class="xref" href="dbopen.html" title="DB->open()">DB->open()</a> method is called.
</p>
<p>
The <code class="methodname">DB->set_append_recno()</code> <span>
<span>
method returns a non-zero error value on failure and 0 on success.
</span>
</span>
</p>
<div class="note" style="margin-left: 0.5in; margin-right: 0.5in;">
<h3 class="title">Note</h3>
<p>
Berkeley DB is not re-entrant. Callback functions should not attempt to make
library calls (for example, to release locks or close open handles). Re-entering
Berkeley DB is not guaranteed to work correctly, and the results are undefined.
</p>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
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<div>
<h3 class="title"><a id="id1642377"></a>Parameters</h3>
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<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
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<div>
<h4 class="title"><a id="id1642335"></a>db_append_recno_fcn</h4>
</div>
</div>
</div>
<p>
The <span class="bold"><strong>db_append_recno_fcn</strong></span> parameter is
a function to call after the record number has been selected but
before the data has been stored into the database. The function takes
three parameters:
</p>
<div class="itemizedlist">
<ul type="disc">
<li>
<p>
<code class="literal">dbp</code>
</p>
<p>
The <span class="bold"><strong>dbp</strong></span> parameter is the enclosing
database handle.
</p>
</li>
<li>
<p>
<code class="literal">data</code>
</p>
<p>
The <span class="bold"><strong>data</strong></span> parameter is the data
<a class="link" href="dbt.html" title="Chapter 4. The DBT Handle">DBT</a> to be stored.
</p>
</li>
<li>
<p>
<code class="literal">recno</code>
</p>
<p>
The <span class="bold"><strong>recno</strong></span> parameter is the generated
record number.
</p>
</li>
</ul>
</div>
<p>
The called function may modify the data
<a class="link" href="dbt.html" title="Chapter 4. The DBT Handle">DBT</a>. If the function needs to allocate
memory for the <span class="bold"><strong>data</strong></span> field, the
<span class="bold"><strong>flags</strong></span> field of
the returned <a class="link" href="dbt.html" title="Chapter 4. The DBT Handle">DBT</a>
should be set to <code class="literal">DB_DBT_APPMALLOC</code>, which indicates that
Berkeley DB should free the memory when it is done with it.
</p>
<p>
The callback function must return 0 on success and
<span class="bold"><strong>errno</strong></span> or a value outside of
the Berkeley DB error name space on failure.
</p>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="id1642468"></a>Errors</h3>
</div>
</div>
</div>
<p>
The <code class="methodname">DB->set_append_recno()</code> <span>
<span>
method may fail and return one of the following non-zero errors:
</span>
</span>
</p>
<div class="sect3" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h4 class="title"><a id="id1642279"></a>EINVAL</h4>
</div>
</div>
</div>
<p>
If the method was called after <a class="xref" href="dbopen.html" title="DB->open()">DB->open()</a>
was called; or if an invalid flag value or parameter was specified.
</p>
</div>
</div>
<div class="sect2" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h3 class="title"><a id="id1642489"></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">
<div>
<div>
<h3 class="title"><a id="id1642398"></a>See Also</h3>
</div>
</div>
</div>
<p>
<a class="xref" href="db.html#dblist" title="Database and Related Methods">Database and Related Methods</a>
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