Python Basics — File Handling

File Handling

Reading and writing files is one of the most practical skills in programming. Python makes it straightforward with built-in functions and powerful libraries for CSV, JSON, and more.

What You’ll Learn

#	Topic	What You’ll Master
1	Reading Files	open(), read modes, iterating lines
2	Writing Files	Write mode, append mode, creating files
3	Context Managers	The with statement — the proper way
4	CSV Files	Reading & writing spreadsheet data
5	JSON Files	Working with API data and config files
6	Practice Exercises	Test your understanding

Quick Preview

# Write a file
with open("notes.txt", "w") as f:
    f.write("Hello, File!\n")
    f.write("Python makes this easy.\n")

# Read a file
with open("notes.txt", "r") as f:
    content = f.read()
    print(content)
# Hello, File!
# Python makes this easy.

# Work with JSON
import json

data = {"name": "Alice", "scores": [85, 92, 78]}
with open("data.json", "w") as f:
    json.dump(data, f, indent=2)

File Modes at a Glance

Mode	Description	File Exists	File Doesn’t Exist
"r"	Read (default)	Opens for reading	FileNotFoundError
"w"	Write	Overwrites content	Creates new file
"a"	Append	Adds to end	Creates new file
"x"	Exclusive create	FileExistsError	Creates new file
"rb"	Read binary	Opens bytes	FileNotFoundError
"wb"	Write binary	Overwrites bytes	Creates new file

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Start Learning: Reading Files →