In the previous pages, we have described arrays that are a single list of key/value pairs. However, sometimes you want to store values with more than one key. For this, we have multidimensional arrays ...

Simple, fast and powerful PHP utility functions to flatten/unflatten multidimensional/JSON arrays into a one-dimensional array, preserving key names and joining them with customizable separators.

I must be losing my mind, because PHP is eating away at my sanity, what the hell am I doing wrong here? I'm obviously new to PHP and coming from a java / ...