Question

can anyone please tell me how to check whether the entered date(24 hour format) in a textbox is valid or not using regular expression?

Answer 1

You should not use a regex to solve this. Use the DateTime.TryParse method.

DateTime dt;

bool bSuccess = DateTime.TryParse("2009-05-01 14:57:32", out dt);
if(bSuccess)
    Console.WriteLine("it's a date!");