$re = '/\d{2}\/\d{2}\/\d{4}/m';
$str = 'AAAAAAAAAA AAAAAAAAAAA - AAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAA
AAAAAAAA em: 20/04/2017
AAAAAAAAAA AAAAAAAAAAA - AAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAA
AAAAAAA em: 20/04/2017
AAAAAAAAAAAAAAAAAAAAAAAA
AAAAAA em: 21/06/2016
AAAAAAAAAA AAAAAAAAAAA - AAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAA
AAAAAA em: 20/04/2017
AAAAAAAAAA AAAAAAAAAAA - AAAAAAAAAAAAA
AAAAAAAAAAAAAAAAAAAA
AAAAAA em: 20/04/2017';
preg_match_all($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