Regex check datetime dd/mm/yyyy or d/m/yyyy

Regex: can use page https://regex101.com to check online:
^((((0?[1-9]|[12]\d|3[01])[\.\-\/](0?[13578]|1[02])[\.\-\/]((1[6-9]|[2-9]\d)?\d{2}))|((0?[1-9]|[12]\d|30)[\.\-\/](0?[13456789]|1[012])[\.\-\/]((1[6-9]|[2-9]\d)?\d{2}))|((0?[1-9]|1\d|2[0-8])[\.\-\/]0?2[\.\-\/]((1[6-9]|[2-9]\d)?\d{2}))|(29[\.\-\/]0?2[\.\-\/]((1[6-9]|[2-9]\d)?(0[48]|[2468][048]|[13579][26])|((16|[2468][048]|[3579][26])00)|00)))|(((0[1-9]|[12]\d|3[01])(0[13578]|1[02])((1[6-9]|[2-9]\d)?\d{2}))|((0[1-9]|[12]\d|30)(0[13456789]|1[012])((1[6-9]|[2-9]\d)?\d{2}))|((0[1-9]|1\d|2[0-8])02((1[6-9]|[2-9]\d)?\d{2}))|(2902((1[6-9]|[2-9]\d)?(0[48]|[2468][048]|[13579][26])|((16|[2468][048]|[3579][26])00)|00))))$

Code java:
final String regex = "^((((0?[1-9]|[12]\\d|3[01])[\\.\\-\\/](0?[13578]|1[02])[\\.\\-\\/]((1[6-9]|[2-9]\\d)?\\d{2}))|((0?[1-9]|[12]\\d|30)[\\.\\-\\/](0?[13456789]|1[012])[\\.\\-\\/]((1[6-9]|[2-9]\\d)?\\d{2}))|((0?[1-9]|1\\d|2[0-8])[\\.\\-\\/]0?2[\\.\\-\\/]((1[6-9]|[2-9]\\d)?\\d{2}))|(29[\\.\\-\\/]0?2[\\.\\-\\/]((1[6-9]|[2-9]\\d)?(0[48]|[2468][048]|[13579][26])|((16|[2468][048]|[3579][26])00)|00)))|(((0[1-9]|[12]\\d|3[01])(0[13578]|1[02])((1[6-9]|[2-9]\\d)?\\d{2}))|((0[1-9]|[12]\\d|30)(0[13456789]|1[012])((1[6-9]|[2-9]\\d)?\\d{2}))|((0[1-9]|1\\d|2[0-8])02((1[6-9]|[2-9]\\d)?\\d{2}))|(2902((1[6-9]|[2-9]\\d)?(0[48]|[2468][048]|[13579][26])|((16|[2468][048]|[3579][26])00)|00))))$";
        final String string = "1/1/2012\n"
             + "10/2/1991\n"
             + "02/12/1999\n"
             + "18/10/1992\n"
             + "30/02/2000\n"
             + "--\n"
             + "13/13/2000\n"
             + "1/13/2000\n"
             + "32/1/2000\n"
             + "30/2/2000\n"
             + "29/2/1999\n\n";

        final Pattern pattern = Pattern.compile(regex, Pattern.MULTILINE);
        final Matcher matcher = pattern.matcher(string);

        while (matcher.find()) {
            System.out.println("Full match: " + matcher.group(0));
//            for (int i = 1; i <= matcher.groupCount(); i++) {
//                System.out.println("Group " + i + ": " + matcher.group(i));
//            }
        }
Code C#:
 public static void Main() {
 string pattern = @ "^((((0?[1-9]|[12]\d|3[01])[\.\-\/](0?[13578]|1[02])[\.\-\/]((1[6-9]|[2-9]\d)?\d{2}))|((0?[1-9]|[12]\d|30)[\.\-\/](0?[13456789]|1[012])[\.\-\/]((1[6-9]|[2-9]\d)?\d{2}))|((0?[1-9]|1\d|2[0-8])[\.\-\/]0?2[\.\-\/]((1[6-9]|[2-9]\d)?\d{2}))|(29[\.\-\/]0?2[\.\-\/]((1[6-9]|[2-9]\d)?(0[48]|[2468][048]|[13579][26])|((16|[2468][048]|[3579][26])00)|00)))|(((0[1-9]|[12]\d|3[01])(0[13578]|1[02])((1[6-9]|[2-9]\d)?\d{2}))|((0[1-9]|[12]\d|30)(0[13456789]|1[012])((1[6-9]|[2-9]\d)?\d{2}))|((0[1-9]|1\d|2[0-8])02((1[6-9]|[2-9]\d)?\d{2}))|(2902((1[6-9]|[2-9]\d)?(0[48]|[2468][048]|[13579][26])|((16|[2468][048]|[3579][26])00)|00))))$";
 string input = @ "1/1/2012
 10 / 2 / 1991
 2 / 12 / 1999
 18 / 10 / 1992
 29 / 02 / 2000
  --
  13 / 13 / 2000
 1 / 13 / 2000
 32 / 1 / 2000
 30 / 2 / 2000
 29 / 2 / 1999

  ";
 RegexOptions options = RegexOptions.Multiline;

 foreach(Match m in Regex.Matches(input, pattern, options)) {
  Console.WriteLine("'{0}' found at index {1}.", m.Value, m.Index);
 }
}