日期正则表达式

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text.RegularExpressions;
public class Program
{
  public static void Main()
  {
    var reg = @"^(?:d{4}/(?:(?:0?[1-9]|1[0-2])/(?:0?[1-9]|1[0-9]|2[0-8])|(?:0?[13-9]|1[0-2])/(?:29|30)|(?:0?[13578]|1[02])/31)|(?:d{2}(?:0[48]|[2468][048]|[13579][26])|(?:[02468][048]|[13579][26])00)/0?2/29)$";
        
    var reg2 = @"^(?:d{4}(?:(?:0?[1-9]|1[0-2])(?:0?[1-9]|1[0-9]|2[0-8])|(?:0?[13-9]|1[0-2])(?:29|30)|(?:0?[13578]|1[02])31)|(?:d{2}(?:0[48]|[2468][048]|[13579][26])|(?:[02468][048]|[13579][26])00)0?229)$";
         
    var str = "2034/05/05";

    var match = Regex.IsMatch(str, reg);
    Console.WriteLine(match);
    str = "20340505";
    str = "203019";
    match = Regex.IsMatch(str, reg2);
    Console.WriteLine(match);

    DateTime dtWork;
    var date = "203012";

    if ( DateTime.TryParseExact(date, "yyyyMMdd", null, System.Globalization.DateTimeStyles.None, out dtWork))
    {
      Console.WriteLine(dtWork);
    }
    else
    {
      Console.WriteLine(dtWork);
    }

    str = "110111";
    var reg3 = @"^(?:(?:(?:(?:(?:1[6-9]|[2-9]d)(?:0[48]|[2468][048]|[13579][26])|(?:(?:16|[2468][048]|[3579][26])00)))(?:0229))|(?:(?:(?:1[6-9]|[2-9]d)d{2})(?:(?:(?:0[13578]|1[02])31)|(?:(?:0[13-9]|1[0-2])(?:29|30))|(?:(?:0[1-9])|(?:1[0-2]))(?:0[1-9]|1d|2[0-8]))))$";
    Console.WriteLine(Regex.IsMatch(str, reg3));

    str = "20190228";
    var reg4 = @"";
    Console.WriteLine(Regex.IsMatch(str, reg4));

  }
}

输出： 

True

True

01/01/0001 00:00:00

False

True