Edd Mann has a post to his site sharing a new screencast about developing PHP extensions by Joe Watkins, specifically about using a resizable-indexed array.

Following on from our first screencast, which touched upon how to setup a PHP extension development environment and creating a simple ‘array_sum’ like function. We now further this topic by implementing a resizable-indexed array class which supplies very similar functionality to that of the SplFixedArray class. Throughout this discussion we look into creating a custom Zend object class, using this to invoke an implemented data-structure located in another file, implementing internal interfaces, object handlers and the importance of PHP extension tests.

You can watch the video either through the in-page video player or directly on YouTube if you'd like a bit more control over the sizing. You can find the resulting code for the extension in this repository on Joe's account.