Sams Teach Yourself PHP in 24 Hours, Third Edition

Saving State Between Function Calls with the static Statement

Variables within functions have a short but happy life on the whole. They come into being when the function is called and die when execution is finished. This is as it should be. It is usually best to build a script as a series of self-contained blocks, each with as little knowledge of others as possible. Occasionally, however, you might want to give a function a rudimentary memory.

Let’s assume we want a function to keep track of the number of times it has been called. Why? In our examples, the function is designed to create numbered headings in a script that dynamically builds online documentation.

We could, of course, use our newfound knowledge of the global statement to do this. ...