$re = '/(?:"[^"]*"[^"]*?\K|(*SKIP))+(?(DEFINE)(?\'d\'d{1,4}|m{1,4}|y{2,4}))(?<![dmy.])((?P>d))\.(?!\2)((?P>d))(?:\.(?!\2|\3)((?P>d)))?(?!\.?[dmy])/mi';
$str = '"DD.MM": DD.MM
"DD.MM.YY": DD.MM.YY
"Форматы внутри строки в кавычках DD.MM.YYYY не учитывать": DD.MM.YYYY "и тут dd.mm тоже"
"Поход: " DD.MM. ", кино:" DD.mm
"Datum kann in der Mitte sein" DD.MM.YYYY "oder sogar an Ende" DD.MM.YY
Форматы без разделителя DDMMYYYY не учитывать
"DD.MM"
DD.MM
DD.MM.DD
DD.MM
"DD.MM"
DD.MM.DD
DD.DD.MM';
preg_match_all($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