The PHPBuilder.com site has a quick reminder about a handy little bit of functionality PHP has to make evaluations quicker - the ternary operator.

This allows you to check for the existence of a variable (or check that the variable has a valid value) and assign a value accordingly. This is very useful when you are dealing with $_GET, $_POST, $_SESSION etc. variables, because you don't know whether the incoming variable will exist, and if it doesn't you might want to assign a default value.

An example is included and explained - evaluating an index in the _GET superglobal to see if it exists. It returns either the value itself or a false.