datechecker.py

import re 
datePattern = re.compile(r'([0-3][0-9])/([0-1][0-2])/((\d){4})')
dateFound = datePattern.search('My birthdate is 31/09/2000')
if not dateFound is None:
    print(dateFound.groups())
    day = dateFound.group(1)
    month = dateFound.group(2).strip("0") # strip என்ன செய்யும் என்று கொஞ்சம் சிந்தியுங்களேன்.  
    year = dateFound.group(3)
    print(day, month, year)
    if int(month) in [1,3,5,7,8,10,12]:
	    if int(day)>31:
	    	print("Invalid Date, Date can't be greater than 31")
    elif int(month) in [4,6,9,11]:
	    if int(day)>30:
	    	print("Invalid Date, Date can't be greater than 30")
    else:
	    if int(day)>29:
	    	print("Invalid Date, Date can't be greater than 29")
	    elif int(day)==29:
		    y = int(year)
		    if not (((y%4)==0) and ((y%100)==0) and ((y%400)==0)):
		    	print("Invalid Date, Date can't be greater than 28")
else:
    print("Invalid Date")