Working with Files

Programs are more useful when they can save data between runs. Python's built-in open() reads and writes files.

Pythonshares state with other Python blocks

with open("scores.txt", "w") as f:
    f.write("Ada,95\n")
    f.write("Grace,98\n")

with open("scores.txt", "r") as f:
    for line in f:
        name, score = line.strip().split(",")
        print(f"{name}: {score}")

with open("scores.txt", "w") as f:
    f.write("Ada,95\n")
    f.write("Grace,98\n")

with open("scores.txt", "r") as f:
    for line in f:
        name, score = line.strip().split(",")
        print(f"{name}: {score}")

The `with` statement

with open(...) as f: opens the file and guarantees it gets closed automatically when the block ends, even if an error happens inside it. Without with, you'd have to remember to call f.close() yourself.

Common modes

Mode	Meaning
`"r"`	Read (default), errors if the file doesn't exist
`"w"`	Write, creates the file or overwrites it completely
`"a"`	Append, adds to the end without erasing existing content

Working with Files

The with statement

Common modes

📝 Files Quiz

The `with` statement