Python: Capitalize the First Letter of Each Word in a File (Solved)

Practice Question 23

In this question, we will learn how to write a function that acts like an “Auto-Corrector.” It will read a file and ensure every word starts with a capital letter (e.g., “once upon a time” becomes “Once Upon A Time”).

The Logic (How it works)

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

To transform text word-by-word, we follow this sequence:

• Open Two Files: Open the source (story.txt) for reading and a new file (newstory.txt) for writing.

• The Split Strategy: Use .read().split() to break the entire text into a list of individual words.

• The .capitalize() Method: This built-in Python function converts the first character of a string to uppercase and the rest to lowercase.

• Reconstructing the File: Write each transformed word into the new file, adding a space after each word so they don’t stick together.

Let’s Code as per the above logic :

def capitalizeFirstLetter():
    f1 = open("story.txt", "r")
    f2 = open("newstory.txt", "w")
    
    data = f1.read()
    wordlist = data.split()
    
    for word in wordlist:
        # .capitalize() turns "python" into "Python"
        cap_word = word.capitalize()
        f2.write(cap_word + " ")
            
    f1.close()
    f2.close()
    print("Content successfully capitalized and saved to newstory.txt")

# To call the function:
capitalizeFirstLetter()

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:

• Handling Empty Files: Always check if len(wordlist) > 0. If you try to access wordlist[0] on an empty file, your program will crash with an IndexError.

• Tie-Breaker: If there are two words of the same smallest length (like “is” and “to”), this logic will keep the first one it found. To get the last one, you would change < to <=.

• Alternative (The min() function): Python has a built-in shortcut: smallest = min(wordlist, key=len). While this is great for real-world coding, using a for loop (as shown above) is usually preferred in Board Exams to show you understand the underlying algorithm.

Teacher’s Secret Tip for Exams:

This exact same structure is used to find the Largest word. Just change smallest = wordlist[0] to largest = wordlist[0] and change the condition to if len(word) > len(largest):

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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