Practice: Leap Year

Lesson

Practice: Leap Year

This exercise combines and, or, not, and the modulo operator from First Steps.

A year is a leap year when:

it is divisible by 4,
except years divisible by 100, which are not leap years,
except years divisible by 400, which are.

So 2024 is a leap year, 1900 is not, and 2000 is.

Recall from First Steps: year % 4 == 0 is True exactly when year is divisible by 4.

Exercise

Define a function named is_leap_year with one parameter, year.
Return True when year is a leap year, otherwise False.

Run your code to see the output, then press Submit.

Hints

Write the three rules as three boolean expressions first, in separate variables if it helps.
One correct shape: divisible by 400, or divisible by 4 and not divisible by 100.
Test your function against all three example years before submitting.

Tests

import unittest


class TestIsLeapYear(unittest.TestCase):
    def test_2024_is_a_leap_year(self):
        self.assertIs(is_leap_year(2024), True)

    def test_2023_is_not_a_leap_year(self):
        self.assertIs(is_leap_year(2023), False)

    def test_1900_is_not_a_leap_year(self):
        self.assertIs(is_leap_year(1900), False)

    def test_2000_is_a_leap_year(self):
        self.assertIs(is_leap_year(2000), True)

    def test_2100_is_not_a_leap_year(self):
        self.assertIs(is_leap_year(2100), False)

Solution

def is_leap_year(year):
    return year % 400 == 0 or (year % 4 == 0 and year % 100 != 0)


print(is_leap_year(2024))
print(is_leap_year(1900))
print(is_leap_year(2000))

Solution hidden. Give it a real try first.

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main.py

Console

Press Run to execute your code, or Submit to test and complete this problem.