The problem
Write a daily expression that validates the gregorian date within the format “DD.MM.YYYY”
Right date examples:
"23.12.2008"
"01.08.1994"
Incorrect examples:
"12.23.2008"
"01-Aug-1994"
" 01.08.1994"
Notes:
- most size of validator is 400 characters to keep away from hardcoding. (shortest answer to this point is 170 characters)
- validator ought to course of leap days (February, 29) accurately.
- the date is Gregorian, it’s vital to find out if yr is leap: https://en.wikipedia.org/wiki/Gregorian_calendar
The answer in Python code
Choice 1:
date_validator = (
'((('
'(0[1-9]|1d|2[0-8]).(0[1-9]|1[012])|' # 01-28 of any month
'(29|30).(0[13-9]|1[012])|' # 29-30 of months, besides February
'(31.(0[13578]|1[02]))).' # 31 of lengthy months
'([1-9]d{3}|d{3}[1-9]))|' # any yr, besides 0000
'(29.02.(' # leap day
'dd([2468][048]|[13579][26]|0[48])|' # leap years (mod 4)
'([2468][048]|[13579][26]|0[48])00' # leap years (mod 400)
')))$' )
Choice 2:
not_0000 = "((?!0+$)d{4})"
not_feb = "(0[13-9]|1[0-2])"
div_4 = "([2468][048]|[13579][26]|0[48])"
day_31 = "(31.(0[13578]|1[02]))"
day_29_30 = "(29|30)"
day_def = "(0[1-9]|1d|2[0-8])"
two_int = "d{2}"
day_29_30_31 = f"({day_31}|{day_29_30}.{not_feb}).{not_0000}"
day_default = f"{day_def}.(02|{not_feb}).{not_0000}"
leap_year = f"(29.02.({two_int}{div_4}|{div_4}00))"
date_validator = f"^({day_29_30_31}|{day_default}|{leap_year})$"
Choice 3:
date_validator = r"^(((0[1-9]|1d|2[0-8]).(0[1-9]|1[0-2])|(29|30).(0[13-9]|1[0-2])|31.(0[13578]|1[02])).(?!0000)d{4}$)|29.02.(?!0000)(([02468][048]|[13579][26])00|d{2}(0[48]|[2468][048]|[13579][26]))$"
Take a look at instances to validate our answer
import re
check.assert_equals(bool(re.match(date_validator,'01.01.2009')),
True, 'Primary appropriate date: 01.01.2009')
check.assert_equals(bool(re.match(date_validator,'01-Jan-2009')),
False, 'Incorrect masks: 01-Jan-2009')
check.assert_equals(bool(re.match(date_validator,'05.15.2009')),
False, 'Incorrect month: 15.15.2009')