days_old.py

# By Websten from forums
# Given your birthday and the current date, calculate your age in days. 
# Account for leap days. 
# Assume that the birthday and current date are correct dates (and no 
# time travel). 
#
def isLeapYear(year):
    if year % 400 == 0:
        return True
    if year % 100 == 0:
        return False
    if year % 4 == 0:
        return True
    return False

def daysInMonths(year, month):
    if month in (1,3,5,7,8,10,12):
        return 31
    else:
        if month == 2:
            if isLeapYear(year):
                return 29
            else:
                return 28
        else:
            return 30

def nextDay(year, month, day):
    if day < daysInMonths(year, month):
        return year, month, day + 1
    else:
        if month == 12:
            return year + 1, 1, 1
        else:
            return year, month + 1, 1
        
def dateIsBefore(year1, month1, day1, year2, month2, day2):
    if year1 < year2:
        return True
    if year1 == year2:
        if month1 < month2:
            return True
        if month1 == month2:
            return day1 < day2
    return False        

def daysBetweenDates(year1, month1, day1, year2, month2, day2):
    days = 0
    while dateIsBefore(year1, month1, day1, year2, month2, day2):
        year1, month1, day1 = nextDay(year1, month1, day1)
        days += 1
    return days

            
            

# Test
def test():
    test_cases = [((2012,1,1,2012,2,28), 58), 
                  ((2012,1,1,2012,3,1), 60),
                  ((2011,6,30,2012,6,30), 366),
                  ((2011,1,1,2012,8,8), 585 ),
                  ((1900,1,1,1999,12,31), 36523)]
    for (args, answer) in test_cases:
        result = daysBetweenDates(*args)
        if result != answer:
            print("Test with data:", args, "failed")
        else:
            print ("Test case passed!")

test()