best date regex mm/dd/yyyy - asp.net

Question

please help me to find the best regex for the dateformat mm/dd/yyy and m/d/yyyy.
i have tried different links but everyone has some problems. so please help me to solve this.
What is the MM/DD/YYYY regular expression and how do I use it in php?
http://regexlib.com/DisplayPatterns.aspx?cattabindex=4&categoryId=5
http://www.regular-expressions.info/regexbuddy/datemmddyyyy.html

Answer 1

Use one of the DateTime.TryParse overloads (or DateTime.TryParseExact if you want more control) to validate whether a string is a valid representation of a DateTime.
DateTime dt;
if(DateTime.TryParse(someInputString, out dt)
{
// it is valid and dt can be used
}
This would be a better approach than regular expressions - it is faster, well tested and will produce a valid DateTime object.

Answer 2

If you need a regular expression then something like this would work (for most cases, since it allows 31st of February).
(0?\d|1[012])\/([012]?\d|3[01])\/\d{4}
Usually it is much better to use DateTime parsing for verifying date formats. Like DateTime.TryParseExact method. You can use the regular expression in the browser (in JavaScript) but you should really use DateTime parsing on the server side.