note 38868 deleted from function.in-array by danbrown

Note Submitter: mark at x2software dot net ---- Reply/addition to melissa at hotmail dot com's note about in_array being much slower than using a key approach: associative arrays (and presumably normal arrays as well) are hashes, their keys are indexed for fast lookups as the test showed. It is often a good idea to build lookup tables this way if you need to do many searches in an array... For example, I had to do case-insensitive searches. Instead of using the preg_grep approach described below I created a second array with lowercase keys using this simple function: <?php /** * Generates a lower-case lookup table * * @param array $array the array * @return array an associative array with the keys being equal * to the value in lower-case */ function LowerKeyArray($array) { $result = array(); reset($array); while (list($index, $value) = each($array)) { $result[strtolower($value)] = $value; } return $result; } ?> Using $lookup[strtolower($whatyouneedtofind)] you can easily get the original value (and check if it exists using isset()) without looping through the array every time...