$re = '/(\d+)(?:st|[nr]d|th)?-?(\d*)(?:st|[nr]d|th)?\s*Apr(?:il)?|Apr(?:il)?\s*(\d+)(?:st|[nr]d|th)?-?(\d*)(?:st|[nr]d|th)?/i';
$str = '02 APR
APR 02
2 APR
APR 2
2nd APR
APR 2nd
2nd April
April 2nd
APR 12th
April 12th
12th April
April 13-16
13-16 April
APR 13-16
13-16 APR
April 13th-16th
13th-16th April
APR 13th-16th
13th-16th APR';
preg_match_all($re, $str, $matches, PREG_SET_ORDER, 0);
// Print the entire match result
var_dump($matches);
Please keep in mind that these code samples are automatically generated and are not guaranteed to work. If you find any syntax errors, feel free to submit a bug report. For a full regex reference for PHP, please visit: http://php.net/manual/en/ref.pcre.php