Online PHP editor | output for 1pvF4

<?php $str = "0/1/2/3/4/5/6/7/8/9/a/b/c/d/e/f"; $lines = array($str); $results = array(); while ($line = array_shift($lines)) { if (preg_match("/(\w+)(?:\/\w+)+/ui", $line, $match, PREG_OFFSET_CAPTURE)) { list($string, $offset) = $match[1]; array_push($lines, sprintf("%s%s", substr($line, 0, $offset + strlen($string)), substr($line, $offset + strlen($match[0][0])) )); array_push($lines, sprintf("%s%s", substr($line, 0, $offset), substr($line, $offset + strlen($string) + 1) )); } else { $results[] = $line; } } print_r($results);