Reading and Writing Files

# Always use 'with', it auto-closes the file
with open("data.txt", "r") as f:
    content = f.read()          # Read entire file as string
    print(content)

# Read line by line (better for large files)
with open("data.txt", "r") as f:
    for line in f:
        print(line.strip())     # strip() removes the \n

# "w" overwrites, "a" appends
with open("output.txt", "w") as f:
    f.write("Line 1\n")
    f.write("Line 2\n")

# Write multiple lines at once
lines = ["Alice,30\n", "Bob,25\n", "Carol,35\n"]
with open("people.csv", "w") as f:
    f.writelines(lines)

import csv

# Read CSV
with open("data.csv", "r") as f:
    reader = csv.DictReader(f)
    for row in reader:
        print(row["name"], row["age"])

# Write CSV
people = [{"name": "Alice", "age": 30}, {"name": "Bob", "age": 25}]
with open("out.csv", "w", newline="") as f:
    writer = csv.DictWriter(f, fieldnames=["name", "age"])
    writer.writeheader()
    writer.writerows(people)