^\d{1,2}\/\d{1,2}\/\d{4}$

(^|\s|\()((([1-9]){1}|([0][1-9]){1}|([1][012]){1}){1}[\/-]((2[0-9]){1}|(3[01]){1}|([01][1-9]){1}|([1-9]){1}){1}[\/-](((19|20)([0-9][0-9]){1}|([0-9][0-9]){1})){1}(([\s|\)|:])|(^|\s|\()((([0-9]){1}|([0][1-9]){1}|([1][012]){1}){1}[\/-](([11-31]){1}|([01][1-9]){1}|([1-9]){1}){1}[\/-](((19|20)([0-9][0-9]){1}|([0-9][0-9]){1})){1}(([\s|\)|:|$|\>])){1}){1}){1}){1}

^(([1-9])|(0[1-9])|(1[0-2]))\/(([0-9])|([0-2][0-9])|(3[0-1]))\/(([0-9][0-9])|([1-2][0,9][0-9][0-9]))$

((0?[13578]|10|12)(-|\/)((0[0-9])|([12])([0-9]?)|(3[01]?))(-|\/)((\d{4})|(\d{2}))|(0?[2469]|11)(-|\/)((0[0-9])|([12])([0-9]?)|(3[0]?))(-|\/)((\d{4}|\d{2})))

^\d{4}[\-\/\s]?((((0[13578])|(1[02]))[\-\/\s]?(([0-2][0-9])|(3[01])))|(((0[469])|(11))[\-\/\s]?(([0-2][0-9])|(30)))|(02[\-\/\s]?[0-2][0-9]))$

((([0][1-9]|[12][\d])|[3][01])[-/]([0][13578]|[1][02])[-/][1-9]\d\d\d)|((([0][1-9]|[12][\d])|[3][0])[-/]([0][13456789]|[1][012])[-/][1-9]\d\d\d)|(([0][1-9]|[12][\d])[-/][0][2][-/][1-9]\d([02468][048]|[13579][26]))|(([0][1-9]|[12][0-8])[-/][0][2][-/][1-9]\d\d\d)

(?#Calandar from January 1st 45 BC to December 31, 9999 in mm/dd/yyyy format) (?! (?:10(?<sep>[-./])(?:0?[5-9]|1[0-4])\k<sep>(?:1582))| #Missing days from 1582 (?:0?9(?<sep>[-./])(?:0?[3-9]|1[0-3])\k<sep>(?:1752)) #or Missing days from 1752 (?# both sets of missing days such not be in the same calendar so remove one or the other) ) (?n:^(?=\d) # the character at the beginning a the sring must be a digit ( (?<month> (0?[13578])|1[02]| #months with 31 days (0?[469]|11)(?!.31)| # months with 30 days 0?2 # February (?(.29) # if feb 29th check for valid leap year (?=.29. (?! #exclude these years from leap year pattern 000[04] #No year 0 and no leap year in year 4 | (?:(?:1[^0-6]|[2468][^048]|[3579][^26])00) (?# centurial years > 1500 not evenly divisible by 400 are not leap year) ) (?:(?:(?:\d\d) # century (?:[02468][048]|[13579][26]) #leap years (?!\x20BC))|(?:00(?:42|3[0369]|2[147]|1[258]|09)\x20BC)) )| # else if not Feb 29 (?!.3[01]) # and day not Feb 30 or 31 ) #end Leap year check ) #end of month check (?<sep>[-./]) # choose a date separator (?<day>0?[1-9]|[12]\d|3[01]) #days between 1-31 (?# The maximum number of days allowed for a month has already been checked for in the month check. If you made it this far the number of day is within the range for the given month) \k<sep> # Match the same date separator choosen before. (?!0000) # There is no year 0 (?<year>(?=(?:00(?:4[0-5]|[0-3]?\d)\x20BC)|(?:\d{4}(?:\z|(?:\x20\d))))\d{4}(?:\x20BC)? # a four digit year. Use leading zeros if needed ) (?(?=\x20\d)\x20|$))? # if there is a space followed by a digit check for time (?<time> ( # 12 hour format (0?[1-9]|1[012]) # hours (:[0-5]\d){0,2} # optional minutes and seconds (?i:\x20[AP]M) # required AM or PM )| # 24 hour format ( [01]\d|2[0-3]) #hours (:[0-5]\d){1,2}) #required minutes optional seconds ?$)

^((((([0-1]?\d)|(2[0-8]))\/((0?\d)|(1[0-2])))|(29\/((0?[1,3-9])|(1[0-2])))|(30\/((0?[1,3-9])|(1[0-2])))|(31\/((0?[13578])|(1[0-2]))))\/((19\d{2})|([2-9]\d{3}))|(29\/0?2\/(((([2468][048])|([3579][26]))00)|(((19)|([2-9]\d))(([2468]0)|([02468][48])|([13579][26]))))))\s(([01]?\d)|(2[0-3]))(:[0-5]?\d){2}$