Change array keys to lowercase - php

Question

I'm looking for a nifty php solution to replace a standard forloop. i dont care at all about the inner workings of my normalize method.
Here is my code:
$pairs=[];
foreach($items as $key => $val){
$key = $this->normalizeKey($key);
$pairs[$key] = $val;
}
private function normalizeKey($key)
{
// lowercase string
$key = strtolower($key);
// return normalized key
return $key;
}
I'd like to learn the PHP language a bit better. I thought array_walk would be nice to use, but that operates on the values and not the keys.
I am looking for a PHP array method that can perform this code instead of a foreach loop.

Answer 1

You want array_change_key_case
$pairs = array_change_key_case($items);

Answer 2

Just for fun, though it requires three functions. You can replace strtolower() with whatever since this can already be done with array_change_key_case():
$pairs = array_combine(array_map('strtolower', array_keys($items)), $items);
Get the keys from $items
Map the array of keys to strtolower()
Combine the new keys with $items values
You can also use an anonymous function as the callback if you need something more complex. This will append -something to each key:
$pairs = array_combine(array_map(function ($v) {
return $v . '-something';
},
array_keys($items)), $items);

Answer 3

You can normalise the keys and store them and their corresponding values in a temporary array and assign it to your original $pairs array.
Like so:
$normalised = [];
foreach($pairs as $key => $value) {
$normalised[$this->normalizeKey($key)] = $value;
};
$pairs = $normalised;
Edit 2022: Or better yet, use #Sherif's answer as it uses a standand library function