Python Program to Check Evil Number

Posted in Python Tutorial

Updated on Oct 31, 2024

By Mari Selvan

👁️ 61 - Views

⏳ 4 mins

💬 1 Comment

Photo Credit to CodeToFun

🙋 Introduction

In the realm of programming, understanding the properties of numbers is a fascinating journey. One interesting concept is that of Evil Numbers.

An Evil Number is a non-negative integer that has an even number of '1' bits in its binary representation.

In this tutorial, we will explore a Python program designed to check whether a given number is an Evil Number.

The program involves converting the decimal number to its binary representation and counting the number of '1' bits.

📄 Example

Let's delve into the Python code that accomplishes this task.

is_evil_number.py

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# Function to count the number of set bits (1s) in binary representation
def count_set_bits(number):
    count = 0
    while number:
        count += number & 1
        number >>= 1
    return count

# Function to check if a number is an Evil Number
def is_evil_number(number):
    # Count the number of set bits in the binary representation
    set_bits_count = count_set_bits(number)

    # If the count of set bits is even, it is an Evil Number
    return set_bits_count % 2 == 0

# Driver program
if __name__ == "__main__":
    # Replace this value with the number you want to check
    number = 15

    # Call the function to check if the number is an Evil Number
    if is_evil_number(number):
        print(f"{number} is an Evil Number.")
    else:
        print(f"{number} is not an Evil Number.")

💻 Testing the Program

To test the program with different numbers, modify the value of number in the code.

Output

15 is an Evil Number.

Run the script to check if the specified number is an Evil Number.

🧠 How the Program Works

The program defines a function count_set_bits that takes an integer number as input and returns the count of set bits (1s) in its binary representation.
The function is_evil_number checks if the count of set bits is even, indicating that the number is an Evil Number.
Inside the main program, replace the value of number with the desired number you want to check.
The program calls the is_evil_number function and prints the result.

📏 Between the Given Range

Let's explore the python code that checks for Evil Numbers in the specified range.

is_evil_number.py

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# Function to check if a number is Evil
def is_evil_number(num):
    binary_representation = bin(num)[2:]
    count_of_ones = binary_representation.count('1')
    return count_of_ones % 2 == 0

# Range from 1 to 10
start_range = 1
end_range = 10

# Display Evil Numbers in the range
evil_numbers = [num for num in range(start_range, end_range + 1) if is_evil_number(num)]

print(f"Evil numbers in the range {start_range} to {end_range}:")
for evil_num in evil_numbers:
    print(evil_num, end=" ")

💻 Testing the Program

Output

Evil numbers in the range 1 to 10:
3 5 6 9 10

The range for this program is fixed from 1 to 10. To test the program, simply run it, and it will display the Evil Numbers in that range.

🧠 How the Program Works

The program defines a function is_evil_number that checks if a given number is an Evil Number based on its binary representation.
It then iterates through the specified range (from 1 to 10), checks each number, and collects Evil Numbers in a list.
Finally, it prints the Evil Numbers in the specified output format.

🧐 Understanding the Concept of Evil Number

Before delving into the code, let's understand the concept of Evil Numbers. An Evil Number is a non-negative integer that has an even number of '1' bits in its binary representation.