Search a PHP array for a matching key - array_ksearch(), array_kisearch()

array_ksearch.php

<?php

/**
 * Search an array recursively looking for a key containing the supplied $search_string
 *
 * array_ksearch() is case-sensitive, where as array_kisearch() is case-insensitive
 *
 * Returns an array containing all matched key(s) and their associated value(s), or an empty array upon no matches
 *
 * @param array  $array
 * @param string $search_string
 *
 * @return array
 */
function array_ksearch(array $array, string $search_string): array {
    $matches = [];

    foreach ($array as $key => $value) {
        if (strstr($key, $search_string)) {
            $matches[$key] = $value;
        }

        if (is_array($value)) {
            if ($recursive_response = array_ksearch($value, $search_string)) {
                $matches = array_merge($matches, $recursive_response);
            }
        }
    }

    return $matches;
}

/**
 * Search an array recursively looking for a key containing the supplied $search_string
 *
 * array_kisearch() is case-insensitive, where as array_ksearch() is case-sensitive
 *
 * Returns an array containing all matched key(s) and their associated value(s), or an empty array upon no matches
 *
 * @param array  $array
 * @param string $search_string
 *
 * @return array
 */
function array_kisearch(array $array, string $search_string): array {
    $matches = [];

    foreach ($array as $key => $value) {
        if (stristr($key, $search_string)) {
            $matches[$key] = $value;
        }

        if (is_array($value)) {
            if ($recursive_response = array_kisearch($value, $search_string)) {
                $matches = array_merge($matches, $recursive_response);
            }
        }
    }

    return $matches;
}