calendar Module¶

The calendar module provides functions for calendar-related operations and generating formatted calendars.

Mental Model

The calendar module is a virtual wall calendar you can query programmatically. Ask it which day of the week a date falls on, whether a year is a leap year, or print an entire month grid. It handles the tedious arithmetic of varying month lengths and weekday offsets so you don't have to.

Basic Calendar Operations¶

Get calendar information for dates.

```python import calendar from datetime import date

Day of week for a specific date¶

d = date(2024, 12, 25) day_name = calendar.day_name[d.weekday()] print(f"2024-12-25 is a {day_name}")

Check if leap year¶

print(f"2024 is leap year: {calendar.isleap(2024)}") print(f"2025 is leap year: {calendar.isleap(2025)}")

Days in month¶

days = calendar.monthrange(2024, 2) print(f"Feb 2024 has {days[1]} days") ```

2024-12-25 is a Wednesday 2024 is leap year: True 2025 is leap year: False Feb 2024 has 29 days

Print Calendars¶

Generate and display formatted calendars.

```python import calendar

Print a month¶

print("December 2024:") print(calendar.month(2024, 12))

Print a year (just first 3 months for brevity)¶

cal = calendar.TextCalendar() for month in range(1, 4): print(calendar.month(2024, month)) ```

December 2024: December 2024 Mo Tu We Th Fr Sa Su 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31

Exercises¶

Exercise 1. Write a function count_leap_years that takes a start year and an end year (inclusive) and returns the number of leap years in that range. Use calendar.isleap(). For example, count_leap_years(2000, 2024) should return 7.

Solution to Exercise 1

```python import calendar

def count_leap_years(start, end): return sum(1 for year in range(start, end + 1) if calendar.isleap(year))

Test¶

print(count_leap_years(2000, 2024)) # 7 print(count_leap_years(1900, 1900)) # 0 (1900 is not a leap year) print(count_leap_years(2000, 2000)) # 1 ```

Exercise 2. Write a function fridays_in_month that takes a year and month and returns the number of Fridays in that month. Use calendar.monthcalendar() to get the weeks. For example, fridays_in_month(2024, 11) should return 5.

Solution to Exercise 2

```python import calendar

def fridays_in_month(year, month): count = 0 for week in calendar.monthcalendar(year, month): if week[calendar.FRIDAY] != 0: count += 1 return count

Test¶

print(fridays_in_month(2024, 11)) # 5 print(fridays_in_month(2024, 12)) # 4 ```

Exercise 3. Write a function last_day_of_month that takes a year and month and returns the last day of that month as a date object. Use calendar.monthrange(). For example, last_day_of_month(2024, 2) should return date(2024, 2, 29).

Solution to Exercise 3

```python import calendar from datetime import date

def last_day_of_month(year, month): _, last_day = calendar.monthrange(year, month) return date(year, month, last_day)

Test¶

print(last_day_of_month(2024, 2)) # 2024-02-29 print(last_day_of_month(2025, 2)) # 2025-02-28 print(last_day_of_month(2024, 12)) # 2024-12-31 ```