<?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>Change Persistence</title>
<link rel="stylesheet" href="gettingStarted.css" type="text/css" />
<meta name="generator" content="DocBook XSL Stylesheets V1.73.2" />
<link rel="start" href="index.html" title="Berkeley DB Programmer's Reference Guide" />
<link rel="up" href="stl_persistence.html" title="Dbstl Persistence" />
<link rel="prev" href="stl_persistence.html" title="Dbstl Persistence" />
<link rel="next" href="section3.html" title="Object Life Time and Persistence" />
</head>
<body>
<div class="navheader">
<table width="100%" summary="Navigation header">
<tr>
<th colspan="3" align="center">Change Persistence</th>
</tr>
<tr>
<td width="20%" align="left"><a accesskey="p" href="stl_persistence.html">Prev</a> </td>
<th width="60%" align="center">Dbstl Persistence</th>
<td width="20%" align="right"> <a accesskey="n" href="section3.html">Next</a></td>
</tr>
</table>
<hr />
</div>
<div class="section" lang="en" xml:lang="en">
<div class="titlepage">
<div>
<div>
<h2 class="title" style="clear: both"><a id="section2"></a>Change Persistence</h2>
</div>
</div>
</div>
<p>
If you modify the object to which an iterator refers by
(*iterator).member_function_call() or (*iterator).data_member = new_value,
you should call iterator->_DB_STL_StoreElement() to store the change,
otherwise the change would be lost after the iterator moves on to
other elements.
</p>
<p>
If you are storing a sequence, and you modified some part of it, you
should also call this function before the iterator moves.
</p>
<p>
And in both cases, if you
specified <span class="bold"><strong>directdb_get</strong></span> as true (this
is the default value), you should call _DB_STL_StoreElement() after
the change and before the next iterator movement OR the next
dereferencing of the iterator by the star or arrow operators, i.e.
iterator::operator* or iterator::operator->,
otherwise the change is also lost.
</p>
<p>
If you update the element by assigning to a dereferenced iterator like
this: <span class="bold"><strong>*iterator = new_element;</strong></span> then you never
have to call _DB_STL_StoreElement(), the change is stored to the
database automatically.
</p>
</div>
<div class="navfooter">
<hr />
<table width="100%" summary="Navigation footer">
<tr>
<td width="40%" align="left"><a accesskey="p" href="stl_persistence.html">Prev</a> </td>
<td width="20%" align="center">
<a accesskey="u" href="stl_persistence.html">Up</a>
</td>
<td width="40%" align="right"> <a accesskey="n" href="section3.html">Next</a></td>
</tr>
<tr>
<td width="40%" align="left" valign="top">Dbstl Persistence </td>
<td width="20%" align="center">
<a accesskey="h" href="index.html">Home</a>
</td>
<td width="40%" align="right" valign="top"> Object Life Time and Persistence </td>
</tr>
</table>
</div>
</body>
</html>
