using System;
using System.Text.RegularExpressions;
public class Example
{
public static void Main()
{
string pattern = @"(?(DEFINE)
(?# Date )
(?# Day ranges )
(?<d_day28>0[1-9]|1\d|2[0-8]|[1-9])
(?<d_day29>0[1-9]|1\d|2\d|[1-9])
(?<d_day30>0[1-9]|1\d|2\d|30|[1-9])
(?<d_day31>0[1-9]|1\d|2\d|3[01]|[1-9])
(?# Month specifications )
(?<d_month28>0?2)
(?<d_month29>0?2)
(?<d_month30>0?[469]|11)
(?<d_month31>0?[13578]|1[02])
(?# Year specifications )
(?<d_year>\d+)
(?<d_yearLeap>(?:\d*?(?:(?:0[48]|[13579][26]|[2468][048])|(?:(?:[02468][048]|[13579][26])00))|[48]00|[48])(?=\D|\b))
(?# Valid date formats )
(?<d_format>
(?&d_day28)-(?&d_month28)-(?&d_year)|
(?&d_day29)-(?&d_month29)-(?&d_yearLeap)|
(?&d_day30)-(?&d_month30)-(?&d_year)|
(?&d_day31)-(?&d_month31)-(?&d_year)
)
)
\b(?&d_format)\b";
string input = @"29-02-2016 - valid
29-02-2017 - invalid (not leap year)
30-03-2016 - valid
29-2-2017 - invalid (not leap year)
28-2-2017 - valid
2-2-2017 - valid
31-11-2017 - invalid (November has 30 days)
30-11-2017 - valid";
RegexOptions options = RegexOptions.Multiline | RegexOptions.IgnorePatternWhitespace;
foreach (Match m in Regex.Matches(input, pattern, options))
{
Console.WriteLine("'{0}' found at index {1}.", m.Value, m.Index);
}
}
}
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 C#, please visit: https://msdn.microsoft.com/en-us/library/system.text.regularexpressions.regex(v=vs.110).aspx