A PHP function to sum values in associative arrays

For a new project, I needed to combine two or more associative arrays and sum the values of any keys that exist in common. I was a little surprised to find that there wasn’t a built-in function to do this in PHP. So I wrote my own. It can accept any number of arrays as arguments, and goes through each array one key at a time, comparing the keys to those in an output array. Where the keys match, the values are summed. If the key does not exist in the output array, it’s appended to it. The function returns an array that contains all of the...

PHP array_insert_after() & array_insert_before()

I need to insert a key/value at a certain position in an associative array. It seems like a common issue. I was surprised to discover there wasn't a straightforward answer. Here is the method I created. If you know of a more efficient method, please let me know in the comments. /* * Inserts a new key/value before the key in the array. * * @param $key * The key to insert before. * @param $array * An array to insert in to. * @param $new_key * The key to insert. * @param $new_value * An value to insert. * * @return * The...