if (in_array($char, $array))
$int/false = $strpos($string, $char);
$int = strlen($string);

$string = implode($array);
$array = str_split($string);
$array = explode($delimiter, $string);

$firstItem = array_shift($array);
$lastItem = array_pop($array);
$key = array_search($char, $close);

$mid = floor(($low + $high) / 2);
$next = ($mid + 1) % count($array);
$prev = ($mid + count($array) - 1) % count($array);