note 129194 added to function.array-rand

for a cryptographically secure version, try this It's a better version. It's almost similar to the 'array_rand', it accepts both '$array' and '$num' to pick one or more random keys out of an array. Also, all the validations are included in this function. <?php /** * Pick one or more random keys out of an array, using a cryptograpically secure rng * discussed+reviewed at https://codereview.stackexchange.com/a/289121/279740 * * @param array $array * @param int $num = 1 * @return int|string|array|null */ function array_rand_secure($array, $num = 1) { if (!is_array($array)) { trigger_error( __FUNCTION__ . "(): expects parameter 1 to be array, " . gettype($array) . " given", E_USER_WARNING ); return null; } $arrayLength = count($array); if ($arrayLength === 0) { trigger_error(__FUNCTION__ . "(): Array is empty", E_USER_WARNING); return null; } if ( filter_var($num, FILTER_VALIDATE_INT) === false || $num <= 0 || ($arrayLength - $num) < 0 ) { trigger_error( __FUNCTION__ . "(): Second argument has to be between 1 and the number of elements in the array", E_USER_WARNING); return null; } $randomIndexes = []; while(count($randomIndexes) < $num) { $randomInt = random_int(0, $arrayLength - 1); if (!in_array($randomInt, $randomIndexes)) $randomIndexes[] = $randomInt; }; $arrayKeys = array_keys($array); $randomKeys = array_map(function ($key) use ($arrayKeys) { return $arrayKeys[$key]; }, $randomIndexes); return count($randomKeys) === 1 ? $randomKeys[0] : $randomKeys; } $tests1 = [ [1, 2, 3, 4, 5, 6, 7, 8, 9], [5, 6, 7], ['a' => 1, 'b' => 2, 'c' => 3], ['zero', 4 => 'four', 9 => 'nine'], ["PEAN"=>0], [], "ABC", 123, ]; foreach ($tests1 as $test) { var_dump(array_rand_secure($test)); } $tests2 = [ ["array" => [1, 2, 3, 4, 5, 6, 7, 8, 9], "num" => 9], ["array" => [1, 2, 3, 4, 5, 6, 7, 8, 9], "num" => 4], ["array" => ['a' => 1, 'b' => 2, 'c' => 3], "num" => 2], ["array" => ['zero', 4 => 'four', 9 => 'nine'], "num" => 2], ["array" => ["PEAN" => 0], "num" => 2], ["array" => [], "num" => 2], ["array" => "ABC", "num" => 2], ["array" => 123, "num" => 2], ["array" => [5, 6, 7], "num" => 0], ]; foreach ($tests2 as $test_data) { var_dump(array_rand_secure($test_data["array"], $test_data["num"])); } ?> ---- Server IP: 45.112.84.4 Probable Submitter: 45.91.157.134 (proxied: 122.163.121.189) ---- Manual Page -- https://php.net/manual/en/function.array-rand.php Edit -- https://main.php.net/note/edit/129194 Del: integrated -- https://main.php.net/note/delete/129194/integrated Del: useless -- https://main.php.net/note/delete/129194/useless Del: bad code -- https://main.php.net/note/delete/129194/bad+code Del: spam -- https://main.php.net/note/delete/129194/spam Del: non-english -- https://main.php.net/note/delete/129194/non-english Del: in docs -- https://main.php.net/note/delete/129194/in+docs Del: other reasons-- https://main.php.net/note/delete/129194 Reject -- https://main.php.net/note/reject/129194 Search -- https://main.php.net/manage/user-notes.php