Python Program to Check Leap Year

Introduction

Determining whether a year is a leap year or not is a common task in calendar-related operations in programming. Leap years are those years that are divisible by 4, except for years which are both divisible by 100 and not divisible by 400. This calculation ensures correct alignment with the astronomical and seasonal year.

In this article, you will learn how to check if a given year is a leap year using leap year program in python. By exploring practical examples for leap year in python, you'll understand how to implement this logic in your Python programs effectively.

Simple Python Program to Check a Leap Year

Basic Leap Year Check

1. Accept a year as input from the user.

2. Apply the leap year conditions using conditional statements.

3. Display the result based on the evaluation.

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   year = int(input("Enter a year: "))
   if (year % 4 == 0 and year % 100 != 0) or (year % 400 == 0):
       print(f"{year} is a leap year.")
   else:
       print(f"{year} is not a leap year.")
   

   This code takes a year as input and checks the leap year conditions. If the year is divisible by 4 and not by 100, or if it is divisible by 400, it is identified as a leap year. Otherwise, it is not.

Leap Year Program in Python using Function

1. Define a function to encapsulate the leap year logic.

2. Use this function to check multiple years easily.

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   def is_leap_year(year):
       return (year % 4 == 0 and year % 100 != 0) or (year % 400 == 0)
   # Example Usage
   years = [1996, 2000, 1900, 2021]
   for year in years:
       if is_leap_year(year):
           print(f"{year} is a leap year.")
       else:
           print(f"{year} is not a leap year.")
   

   This snippet defines a is_leap_year function that returns True if the passed year is a leap year and False otherwise. The function is then used to check a list of years and print whether each year is a leap year.

How to Calculate Leap Year in Python

The leap year calculation follows the formula: leap_year = (year % 4 == 0 and year % 100 != 0) or (year % 400 == 0) This formula helps determine if a given year qualifies as a leap year based on divisibility rules.

Leap Year Formula in Python

A concise formula to determine a leap year in Python is: leap = (year % 4 == 0 and year % 100 != 0) or (year % 400 == 0) This formula is used in different implementations to verify leap years efficiently.

Alternative Approach to Check Leap Years Using calendar Module

Python provides a built-in module called calendar, which has a function to check leap years:

Benefits of Using calendar.isleap():

1. Reduces code complexity.

2. Uses Python's built-in optimization.

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   import calendar
   # User input
   year = int(input("Enter a year: "))
   # Check using calendar module
   if calendar.isleap(year):
       print(f"{year} is a leap year.")
   else:
       print(f"{year} is not a leap year.")
   

Conclusion

Checking whether a year is a leap year in Python can be easily implemented using basic arithmetic operations and conditional statements. By abstracting this logic into a function, you enhance code reusability and maintainability. Use these examples as a starting point to integrate leap year calculations into your Python applications, ensuring accurate date and time handling in various functionalities.