Regular expression in C#.net

4
votes

i needed a function for validate the entered date. whether entered date is in correct format. i browsed the web and got a regular expression for it. Its works fine except when you enter 12/12/YYYY(on any year) it shows error saying that its not a valid date.

bool IsDate(string date)  
        {
            Match dobMatch = Regex.Match(date, @"^(((0[1-9]|[12]\d|3[01])\/(0[13578]|1[02])\/((19|[2-9]\d)\d{2}))|((0[1-9]|[12]\d|30)\/(0[13456789]|1[012])\/((19|[2-9]\d)\d{2}))|((0[1-9]|1\d|2[0-8])\/02\/((19|[2-9]\d)\d{2}))|(29\/02\/((1[6-9]|[2-9]\d)(0[48]|[2468][048]|[13579][26])|((16|[2468][048]|[3579][26])00))))$");
            if (!dobMatch.Success)
            {return true;}
            else
            {return false;}
        }

i

4
c#regex

4 Answers

6
votes

Try DateTime.TryParse().

This parses dates for you. This method allows you to pass the CultureInfo if the culture you want to use to parse the date with.

Alternatively, if you really want to use regular expressions, have a look at http://regexlib.com/. That is a comprehensive library of regular expressions with ratings per regular expression.

2
votes

Why don't you use DateTime.TryParse or DateTime.TryParseExact far easier than using a Regex.

1
votes

A regular expression only validates the character data in a string and does not say anything about the actual validity of the data in that string.

To check a string as a valid date in .Net use the following:

DateTime dt;
if (DateTime.TryParse(someString, out dt))
{
   //Parsed as a valid date whose value is now in the variable dt
}
else 
{
   //Not a valid date
}
1
votes

Use:

^([0]?[1-9]|[1|2][0-9]|[3][0|1])[./-]([0]?[1-9]|[1][0-2])[./-]([0-9]{4}|[0-9]{2})$

Or go to following link , http://regexlib.com/DisplayPatterns.aspx?cattabindex=4&categoryId=5