python - How to determine whether a year is a leap year?

Question

I am trying to make a simple calculator to determine whether or not a certain year is a leap year.

By definition, a leap year is divisible by four, but not by one hundred, unless it is divisible by four hundred.

Here is my code:

def leapyr(n):
    if n%4==0 and n%100!=0:
        if n%400==0:
            print(n, "is a leap year.")
    elif n%4!=0:
        print(n, "is not a leap year.")
print(leapyr(1900))

When I try this inside the Python IDLE, the module returns None. I am pretty sure that I should get 1900 is a leap year.

Answer 1

Use calendar.isleap:

import calendar
print(calendar.isleap(1900))