File Handling

Opening files

Use open() with a mode: 'r' (read), 'w' (write), 'a' (append). Always close or use with.

# Using 'with' automatically closes the file
with open("example.txt", "w") as f:
    f.write("Hello, file!")

Reading files

Read the entire file, line by line, or into a list.

with open("example.txt", "r") as f:
    content = f.read()
    print(content)

Try it yourself

Run the example below. Edit it and see what changes.

# File handling demo (conceptual)
data = "Hello from PyLearn!"
print(data)
print(len(data), "characters")
 

Common mistakes

• ⚠Forgetting to close files — use 'with' to auto-close.
• ⚠Opening in 'w' mode erases existing content — use 'a' to append.
• ⚠FileNotFoundError when the file doesn't exist in 'r' mode.