Python: Count the number of Monday of the 1st day of the month between two years

Last update on July 22 2025 11:12:14 (UTC/GMT +8 hours)

24. Count First Mondays

Write a Python program to count the number of Mondays on the 1st day of the month from 2015 to 2016.

Sample Solution:

Python Code:

# Import the datetime module
import datetime
# Import the datetime class from the datetime module
from datetime import datetime

# Initialize a counter to count occurrences of Monday being the first day of the month
monday1 = 0

# Define a range of months from 1 to 12
months = range(1, 13)

# Iterate over years from 2015 to 2016 (inclusive)
for year in range(2015, 2017):
    # Iterate over each month in the range
    for month in months:
        # Check if the first day of the month (year, month, 1) falls on a Monday (weekday() == 0)
        if datetime(year, month, 1).weekday() == 0:
            # If the first day of the month is a Monday, increment the counter
            monday1 += 1

# Print the total count of occurrences where Monday is the first day of the month
print(monday1)

Output:

3

Explanation:

In the exercise above,

• The code imports the "datetime" module, which provides functionalities for dates and times. It also imports the "datetime" class from the "datetime" module.
• Initializing variables:
• It initializes a variable 'monday1' to count occurrences where Monday is the first day of the month. This is initially set to 0.
• Iterating over years and months:
• It iterates over the years from 2015 to 2016 (inclusive) using a for loop.
• Within each year, it iterates over each month (from 1 to 12) using another for loop.
• Check first day of each month:
• For each combination of year and month, it checks if the first day of that month falls on a Monday (weekday() == 0) using the "weekday()" method of the "datetime" object.
• If the first day of the month is a Monday, it increments the 'monday1' counter.
• Finally it prints the total count of occurrences where Monday is the first day of the month.

Flowchart:

For more Practice: Solve these Related Problems:

• Write a Python program to count the number of times the 1st day of the month is a Monday within a given range of years.
• Write a Python function to iterate over a range of years and count how many months start on a Monday, then display the result.
• Write a Python script to generate all first-of-the-month dates for a range and then filter those that are Mondays.
• Write a Python program to determine the frequency of Mondays falling on the first day of the month for two consecutive years and compare the counts.

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• Python Datetime Exercises Home ↩
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