Python File Handling — Read, Write, and Process Files

Basic File Operations

# Always use context managers
with open('data.txt', 'r') as f:
    content = f.read()

# Reading line by line
with open('data.txt', 'r') as f:
    for line in f:
        print(line.strip())

# Writing to a file
with open('output.txt', 'w') as f:
    f.write('Hello, World!\n')

Working with CSV

import csv

with open('data.csv', 'r') as f:
    reader = csv.DictReader(f)
    for row in reader:
        print(row['name'], row['email'])

Working with JSON

import json

with open('config.json', 'r') as f:
    config = json.load(f)

data = {'users': [{'name': 'Alice'}]}
with open('output.json', 'w') as f:
    json.dump(data, f, indent=2)

Pathlib (Modern Approach)

from pathlib import Path

p = Path('data') / 'files' / 'output.txt'
p.write_text('Hello!')
content = p.read_text()

for file in Path('data').glob('*.txt'):
    print(file.name)