Python: Copy Even-Length Words to a New File (Solved)

Practice Question 19

In this question, we will write a function that reads a source file and “extracts” only the words that have an even number of characters (like “code”, “it”, or “Python”), saving them into a separate file.

The Logic (How it works)

Before writing the code, let us first understand the logic behind the solution.

To filter words by their length, we use a simple mathematical check:

• Open Two Files: Open the source file (words.txt) in read mode and the destination file (even.txt) in write mode.

• Read and Split: Convert the source text into a list of words using .split().

• The Length Check: Use len(word) to get the count of characters.

• The Modulus Check: A number is even if it is perfectly divisible by 2. We check this using len(word) % 2 == 0.

• Write to File: If the condition is met, write that word followed by a space into the new file.

Let’s Code as per the above logic :

def copyEvenLengthWords():
    f1 = open("words.txt", "r")
    f2 = open("even.txt", "w")
    
    data = f1.read()
    wordlist = data.split()
    
    for word in wordlist:
        if len(word) % 2 == 0:
            f2.write(word + " ")
            
    print("Even-length words have been copied successfully!")
    
    f1.close()
    f2.close()

# To call the function:
copyEvenLengthWords()

Important Notes for Students

As a teacher, I want you to pay close attention to these points, as they are where most students make mistakes in exams:

• The Modulus Operator (%): This operator gives the remainder of a division. If length % 2 is 0, the number is Even. If it is 1, the number is Odd.

• Adding Spaces: When writing to the new file, we use f2.write(word + " "). If you don’t add the " ", all the words will stick together like one giant word (e.g., “codeitPython”).

• Efficiency: This approach is very clean for board exams because it clearly shows the “Input -> Process -> Output” flow.

Teacher’s Secret Tip for Exams:

f the examiner asks you to copy Odd-length words, just change the condition to if len(word) % 2 != 0: or if len(word) % 2 == 1:. The rest of the logic remains identical!

Want to practice more? If you found this helpful, I have compiled a full list of 30 practice problems just like this one. Each question focuses on a different logic to help you become a pro at File Handling.

Click here to view the full 30-Question Practice Set

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