التعامل مع الملفات

# "w" = write (creates file, or ERASES existing content!)
with open("notes.txt", "w", encoding="utf-8") as f:
    f.write("Buy groceries\n")
    f.write("Call mom\n")

# "a" = append (adds to the end, keeps old content)
with open("notes.txt", "a", encoding="utf-8") as f:
    f.write("Study Python 1 hour\n")

# "r" = read
with open("notes.txt", "r", encoding="utf-8") as f:
    for line in f:
        print("-", line.strip())

import csv

expenses = [
    ["date", "category", "amount"],
    ["2026-09-01", "food", 320],
    ["2026-09-02", "transport", 85],
    ["2026-09-02", "food", 150],
]

with open("expenses.csv", "w", newline="", encoding="utf-8") as f:
    csv.writer(f).writerows(expenses)

# Read back and total by category
totals = {}
with open("expenses.csv", "r", encoding="utf-8") as f:
    for row in csv.DictReader(f):       # each row becomes a dict
        cat = row["category"]
        totals[cat] = totals.get(cat, 0) + int(row["amount"])

print(totals)