🎯 What you will learn
- Write and read text files
- Use with to open files safely
- Handle specific exceptions
👋 Let’s get started!
Programs forget everything when they stop… unless they save to a FILE 💾. High scores, notes, settings — all live in files. Let’s write and read them safely.
🪜 Step by step
1. ✍️ Writing
“w” writes (and replaces). with closes the file automatically.
with open("notes.txt", "w") as f:
f.write("Buy milk\n")
f.write("Practice Python\n")2. 📖 Reading
Read the whole file or loop line by line.
with open("notes.txt") as f:
for line in f:
print("-", line.strip())3. 🛡️ Specific exceptions
Catch the exact error you expect, and use finally for clean-up.
try:
with open("missing.txt") as f:
print(f.read())
except FileNotFoundError:
print("No file yet — starting fresh!")🧪 Try it!
Change the code and press ▶ Run to see what happens. You can’t break anything!
High-score saver
scores = {"Ana": 120, "Ben": 95}
with open("scores.txt", "w") as f:
for name, s in scores.items():
f.write(f"{name},{s}\n")
with open("scores.txt") as f:
for line in f:
name, s = line.strip().split(",")
print(f"{name}: {s} points")Append to a log
with open("log.txt", "a") as f:
f.write("Game started\n")
print("Saved!")📖 Key words
Tap a card to flip it over!
- File mode
- "r" read, "w" write, "a" append 📝
- with
- Opens and auto-closes a file 🔒
- Exception
- An error you can catch 🛡️
- finally
- Runs no matter what 🧹
🏆 Challenge
Write the three colors to colors.txt (one per line), then read the file and print how many lines it has.
Challenge
colors = ["red", "green", "blue"]
Knowledge Check Quiz
- Which mode adds to the end of a file?
- Why use with open(…)?
- Which error happens if the file doesn’t exist?