Why would I want to use PHP’s filter library? Why wouldn’t I?
It seems to try and do a bit of clean-up (it’s awful when you have to work with regular expressions), but on the other hand function naming and parameter constants seem to be a disaster, if you ask me. It must have been included in PHP for a reason, but I just don’t seem to like it. What am I missing?
Later edit:
Regarding GaryF’s answer, I wish to explain a bit why I don’t like this function. This isn’t about using it in ‘my case’ if it fits. This is about using it wherever it fits. There’s a high chance of needing a filter that won’t fit PHP’s functions, so I’ll have to create my own filter. In that case, the application will use two completely different kinds of functions for data filtering. I consider that to be a much worse practice than just inventing a better wheel.
My stance is that the concept of filtering input data is flawed on a conceptual level. See my reply to the almost similar question What’s the best method for sanitizing user input with PHP?