Question

How can i be able to ensure that a selected date time value is between a given time range.
i.e

2/2/2011 8:10:30 is invalid but
2/2/2011 8:30:00 is a valid date

Answer 1

Regular expressions match strings, not numbers or number ranges. Therefore you need to think about the textual representation of all valid times/dates and analyze them.

A number between 5 and 11 would therefore be 1[01]|[5-9] etc.; this can get arbitrarily complex with dates, especially if you need to validate user input. Then your regex needs to know about leap years and all that – all of which is possible but nightmarish to maintain. So you really need to think about if it’s really a regex you want…

For the range 8:30:00-13:00:00 you get (written here as a verbose regex):

\b            # start of word
(?:           # Either match...
 13:00:00     # 13:00:00
|             # or
 (?:          # hours:
  1[012]      # 10-12
  |           # or
  0?9         # 9, optional leading 0
 )            # end of hours
 :            # colon
 [0-5][0-9]   # minutes: 00-59
 :            # colon
 [0-5][0-9]   # seconds
|             # or
 0?8          # hour: (0)8
 :            # colon
 [3-5][0-9]   # minutes 30-59
 :            # colon
 [0-5][0-9]   # seconds
)             # end of alternation.
\b            # end of word

See why this isn’t a good idea?