This Python File Handling lesson is for a beginner. Read the short notes, run each example, then change one name or number and run it again.
open reads or writes a file. The mode \"r\" reads text, \"w\" writes and clears the file, and \"a\" adds to the end.
A with block closes the file even when an error happens. That is the form to use.
Example 1: Start here
This browser runner has no project folder, so file demos stay small here.
from pathlib import Path # load a tool that comes with Python
print(Path("notes.txt").name)
print("Use with open(...) as handle on your machine.")
Example 2: Read lines from text
splitlines is the same shape as looping over a file. The browser runner has no project folder, so the sample stays in a string.
sample = "Python\nSQL\n" # text
print(sample.splitlines()) # one list item for each line
Example 3: Build the text you would write
On your computer, write this text inside a with open(path, \"w\", encoding=\"utf-8\") block.
lines = ["name=Asha\n", "city=Chennai\n"] # a list; the values stay in this order
print("".join(lines)) # join the pieces into one text
Example 4: Use a memory file
StringIO behaves like a file but keeps the text in memory, so this page can run it.
import io # load a tool that comes with Python
handle = io.StringIO() # one object
handle.write("Python\n")
print(handle.getvalue())
This browser runner has no project folder, so file demos stay small here.
