How to convert all keys in a multi-dimenional array to snake_case?

Question

I am trying to convert the keys of a multi-dimensional array from CamelCase to snake_case, with the added complication that some keys have an exclamation mark that I\'d like rem

Answer 1

You can run a foreach on the arrays keys, this way you'll rename the keys in-place:

function transformKeys(&$array) {
    foreach (array_keys($array) as $key) {
        # This is what you actually want to do with your keys:
        #  - remove exclamation marks at the front
        #  - camelCase to snake_case
        $transformedKey = ltrim($key, '!');
        $transformedKey = strtolower($transformedKey[0] . preg_replace('/[A-Z]/', '_$0', substr($transformedKey, 1)));
        # Store with new key
        $array[$transformedKey] = &$array[$key];
        unset($array[$key]);
        # Work recursively
        if (is_array($array[$transformedKey])) {
            transformKeys($array[$transformedKey]);
        }
    }
}