L10Q31_FinishDaysBetweenDates.py

# Credit goes to Websten from forums
#
# Use Dave's suggestions to finish your daysBetweenDates
# procedure. It will need to take into account leap years
# in addition to the correct number of days in each month.

def isLeapYear(year):
    if year % 4 == 0:
        if year % 100 == 0:
            if year % 400 == 0:
                return True
        else:
            return True
    else:
        return False
    return False

def daysInMonth(year, month):
    if month == 1 or month == 3 or month == 5 or month == 7 or month ==8 or month == 10 or month ==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 < daysInMonth(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):
    """Returns True if year1-month1-day1 is before year2-month2-day2. Otherwise, returns False."""
    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):
    """Returns the number of days between year1/month1/day1
       and year2/month2/day2. Assumes inputs are valid dates
       in Gregorian calendar."""
    # program defensively! Add an assertion if the input is not valid!
    assert not dateIsBefore(year2, month2, day2, year1, month1, day1)
    days = 0
    while dateIsBefore(year1, month1, day1, year2, month2, day2):
        year1, month1, day1 = nextDay(year1, month1, day1)
        days += 1
    return days

def test():
    assert daysBetweenDates(2013,1,1,2013,1,1) == 0
    assert daysBetweenDates(2013,1,1,2013,1,2) == 1
    assert nextDay(2013, 1, 1) == (2013, 1, 2)
    assert nextDay(2013, 4, 30) == (2013, 5, 1)
    assert nextDay(2012, 12, 31) == (2013, 1, 1)
    assert nextDay(2013, 2, 28) == (2013, 3, 1)
    assert nextDay(2013, 9, 30) == (2013, 10, 1)
    assert nextDay(2012, 2, 28) == (2012, 2, 29)
    assert nextDay(2013, 9, 30) == (2013, 10, 1)
    assert daysBetweenDates(2013, 1,1,2014,1,1) == 365
    assert daysBetweenDates(2012, 1,1,2013,1,1) == 366
    print 'tests finished'

    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()