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<concept id="GUID-F765C7EB-A8C6-50C0-B350-85BE04C8984F" xml:lang="en"><title>Doubly

linked lists</title><shortdesc>This document is a introduction to doubly linked lists.</shortdesc><prolog><metadata><keywords/></metadata></prolog><conbody>

<p>A doubly linked list is one where each element has pointers forwards to

the next element and backwards to the previous element. The list is circular

- the last element points forwards to an anchor point, and the anchor point

points back to the last element. </p>

<p>Anchor points are always referred to as <i>headers</i>.</p>

<p>A doubly linked list is useful for maintaining a circular queue of items.</p>

<fig id="GUID-1D25A6C6-B294-554E-9EDD-20F8BA05FB07">

<image href="GUID-B0391618-0681-5E4E-94BE-C0E24B862AEF_d0e213571_href.png" placement="inline"/>

</fig>

<p>Doubly linked lists involve the creation and use of the classes:</p>

<ul>

<li id="GUID-68B5EDB3-EE3B-5186-9F79-CE1F307B8DA1"><p><codeph>TDblQueLink</codeph> </p> </li>

<li id="GUID-5F281C65-DD6E-5862-A465-C11D8A515CFA"><p><codeph>TDblQue&lt;class

T&gt;</codeph> </p> </li>

<li id="GUID-7A9DD0CC-4F91-5C24-85FE-D91696257A5C"><p><codeph>TDblQueIter&lt;class

T</codeph> </p> </li>

</ul>

<p>In practice, these classes are almost always used as components of other

classes.</p>