Arrays in PHP are farily unique in that most languages at that level offer lists and tables (or dictionaries) as separate structures. PHP puts them together in the one structure, with some slightly odd behaviours with keys as a result.

Arrays are very powerful in PHP, even with a slightly clunky literal notation. You've been exploring using them as a large structure, but they can do a lot of very clever things when treated as a small structure, as well (my favourite is using a short array literal to send named parameters to a function). And nesting! Don't be afraid to next arrays: you can win a lot of organisation using nested loops and nested arrays. And you can learn and use all of that without using things like array_merge(), by the way.

Wade.

array_diff I use a little, though carefully. array_merge I don't use - it's a little bit simplistic for they way I often work with arrays that need that operation; the + operator works much better.

OTOH, I use array_filter a bit.

Wade.