Write User Input to a File in Python (Step-by-Step Guide)

Working with files in Python often involves reading existing data, but equally important is the ability to write new information to files. A common and practical use case is saving user input into a text file, whether for keeping notes, creating logs, or storing simple data.

In this tutorial, we’ll explore how to take input from a user and write it to a file step by step.

Why Write User Input to a File?

Persistence: Unlike variables that vanish once a program ends, files allow data to be saved permanently.
User Interaction: Programs can collect and save user-generated content, making them more dynamic.
Practical Applications: Writing notes, saving configuration data, logging user activity, and much more.

Step 1: Collecting User Input

Python’s built-in input() function is the simplest way to take input from a user. Let’s say we want the user to enter three lines of notes:

# Collecting three lines of input
lines = []
for i in range(3):
    user_input = input(f"Enter line {i + 1}: ")
    lines.append(user_input)

Here, we store each line in a list for later writing.

Step 2: Opening a File in Write Mode

To write data to a file, we use the open() function with the "w" mode (write mode).

file = open("notes.txt", "w")

"w" mode creates a new file if it doesn’t exist.
If the file already exists, it overwrites the existing content.

Step 3: Writing Input to the File

We can now write the collected input to the file. Each line should be followed by a newline character (\n) to ensure proper formatting.

for line in lines:
    file.write(line + "\n")

Finally, don’t forget to close the file:

file.close()

Step 4: Using a Context Manager (Recommended Way)

Instead of manually closing the file, we can use a with statement. This automatically closes the file after the block is executed, even if errors occur.

with open("notes.txt", "w") as file:
    for i in range(3):
        user_input = input(f"Enter line {i + 1}: ")
        file.write(user_input + "\n")

This approach is cleaner and safer.

Step 5: Verifying the Output

After running the program and entering some lines, open notes.txt. You’ll see the text you entered stored line by line.

Example:

Enter line 1: Python is amazing
Enter line 2: File handling is powerful
Enter line 3: This is saved forever

Contents of notes.txt:

Python is amazing
File handling is powerful
This is saved forever

Best Practices

Always use context managers (with open(...)) to handle files safely.
Validate user input if necessary (e.g., check for empty strings).
If you want to append instead of overwrite, use "a" mode instead of "w".

Conclusion

Writing user input to a file is a fundamental step in making Python programs interactive and useful. With just a few lines of code, you can create programs that save notes, logs, or even structured data provided by the user.