Question

Would it be possible to combine an arrays keys to create a new key using the combined key values?

I’m not asking to create a function to combine them, just wondering if it is possible to do something like this (obviously this code doesn’t work, just showing what I meant in code):

<?php
$box = array(
    "Width" => 10,
    "Height" => 20,
    "Total" => ($box["Width"] + $box["Height"]),
);
echo $box["Total"]; // would show up as 30
?>

Answer 1

No, not while the array is being defined. array(...) is being evaluated first, the result of which is assigned = to $box. You can’t refer to $box before the evaluation is finished.

You’ll have to do it in two steps, or perhaps create a custom class that can do such magic using methods and/or (automagic) getters.