PythonHow-ToBeginner · 3 min read

How to Write to a File in Python: Simple Guide

To write to a file in Python, use the open() function with mode 'w' or 'a' to open the file, then call write() on the file object. Always close the file or use a with block to handle it safely.

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Syntax

Use open(filename, mode) to open a file. The mode can be 'w' to write (overwrite) or 'a' to append. Then use write() to add text. Finally, close the file or use with to auto-close.

python

with open('filename.txt', 'w') as file:
    file.write('Your text here')

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Example

This example writes a greeting message to a file named greeting.txt. It uses with to open the file safely and writes a line of text.

python

with open('greeting.txt', 'w') as file:
    file.write('Hello, friend!\n')
    file.write('Welcome to Python file writing.')

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Common Pitfalls

Forgetting to close the file can cause data loss or locked files.
Using 'w' mode overwrites existing content, so use 'a' to add without deleting.
Writing non-string data without converting causes errors.

python

wrong:
file = open('data.txt', 'w')
file.write(str(123))  # Convert number to string
file.close()

right:
with open('data.txt', 'a') as file:
    file.write(str(123))  # Convert number to string

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Quick Reference

Remember these modes when writing files:

Mode	Description
'w'	Write mode - creates or overwrites file
'a'	Append mode - adds to end of file
'x'	Create mode - creates file, errors if exists
'b'	Binary mode - for non-text files
't'	Text mode - default for text files

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Key Takeaways

Use with open(filename, 'w') to write and auto-close files safely.

Mode 'w' overwrites files; use 'a' to add without deleting.

Always write strings; convert other data types with str().

Closing files is important to save data and free resources.

Use file modes carefully to avoid accidental data loss.