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File Handling
Prerequisites: Basic error handling
open() reads from or writes to a file. The with statement
automatically closes the file afterward, even if an error occurs inside
the block.
with open("notes.txt", "w") as file:
file.write("Hello, file!")
with open("notes.txt", "r") as file:
content = file.read()
print(content)
Expected output
Hello, file!
"w" opens for writing (overwrites existing content), "r" for reading,
and "a" appends to the end without erasing what's already there.
Common mistakes
- Forgetting
with, and forgetting to call.close()manually — an unclosed file can lose unsaved data or lock the file for other programs.