$re = '/(https?):\/\/([0-9a-z.\-\/]+)/';
$str = '<div class="filefield-file"><img class="filefield-icon field-icon-application-vnd-ms-excel" alt="application/vnd.ms-excel icon" src="http://uristhome.ru/sites/all/modules/filefield/icons/x-office-spreadsheet.png"><a href="https://uristhome.ru/sites/default/files/doc/ks-6a.xls" type="application/vnd.ms-excel; length=51712" title="ks-6a.xls">Типовой бланк и форма КС-6а</a></div>
';
preg_match_all($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