← Python

File Operations – Open

open() opens a file and returns a file object; the with statement closes it automatically when done

Part of: Python Coding — Module 44, VCE Software Development - U3O1 - Programming — Module 107, VCE Software Development - U4O1 - development and evaluation — Module 52, QCE Digital Solutions Unit 3 — Innovative Digital Solutions — Module 39, QCE Digital Solutions Unit 4 — Prototype Digital Data Exchanges — Module 76, WA Computer Science ATAR Year 11 — Network Communications — Module 148

Understanding File Operations – Open in Python

What it does: The with statement automatically closes the file when the block ends. 'a' mode opens the file and adds to the end without erasing existing content. open() connects your program to a file on disk — you then read or write through that connection. 'r' requires the file to exist — only 'w' and 'a' create files automatically. Unclosed files may not flush writes to disk and waste OS file handles. Opening a non-existent file in 'r' mode raises FileNotFoundError. Use try/except. 'w' mode creates or overwrites the file. f.write() writes the string. open() returns a file object. type() shows its class name.

Common mistakes: Missing colon after the with statement. open is lowercase: Open is not valid.

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This module's key terms are also in a printable crossword (Modules 41–50) and word search (Modules 41–63).

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Learning
Duo
What does open() do?
Opens a file for reading or writingOpens a website
Matches
❌ f = open('data.txt') print(f.read()) f.write('hi')
↓
Error: Can't write in read mode
Applying
Meanings
Term
open()
Meaning
Built-in function that opens a file.
Practice
with open('hello.txt', 'w') as f:
Testing
Gaps
with ('file.txt', 'r') as f:
Check Answer
Spots
1with open('file.txt') as f
2 content = f.read()

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Quick Questions

1. What does open() do?
A. Opens a website
B. Opens a file for reading or writing ✓
open() connects your program to a file on disk — you then read or write through that connection
2. What does 'r' mode mean?
A. Read only ✓
B. Run
'r' is the default mode — it opens the file for reading and fails if file doesn't exist
3. What does 'w' mode do?
A. Writes overwrites existing content ✓
B. Reads the file
'w' creates the file if needed and wipes any existing content before writing
4. What does 'a' mode do?
A. Appends adds to the end ✓
B. Reads all
'a' keeps existing content and adds new content after it — safe for logs
5. Why use 'with open()'?
A. It's faster
B. Automatically closes the file ✓
with ensures the file closes even if an error occurs — no manual .close() needed

Match the Pairs

f = open('data.txt') print(f.read()) f.write('hi') → Error: Can't write in read mode
open('missing.txt', 'r') → Error: FileNotFoundError
with open('f.txt', 'r') as f: data = f.read() → Valid: with auto-closes file
open('f.txt', 'a') → Ok: Append mode — adds to end
with open('f.txt','w') as f: f.write('Hi') → Output: (writes 'Hi' to file)
f = open('f.txt','r') print(type(f)) → Output: <class '_io.TextIOWrapper'>

Key Term

open()
Built-in function that opens a file.~~'r' mode

Fill in the Blanks

1. with open('file.txt', 'r') as f:
2. with open('file.txt', 'r') as f:
3. with open('file.txt', 'w') as f:
4. with open('log.txt', 'a') as f: f.write('entry')
5. f = open('test.txt', 'w') f.write('Hi') f.close()

Spot the Error

Question 1
A with open('file.txt') as f
B content = f.read()
C print(content)
D print('Done')
Line A — Missing colon after the with statement
Question 2
A with Open('file.txt') as f:
B content = f.read()
C print(content)
D print('Done')
Line A — open is lowercase: Open is not valid
Question 3
A # Open without with block
B f = open('file.txt', 'r')
C content = f.read()
D # forgot to close
Line B — File is never closed: always close or use 'with'
Question 4
A with open('file.txt', 'r') as f:
B f.write('Hello')
C print('Written')
D print('Done')
Line B — Can't write in 'r' mode: use 'w' or 'a'
Question 5
A with open(file.txt, 'r') as f:
B content = f.read()
C print(content)
D print('Done')
Line A — Filename must be a string in quotes: 'file.txt'

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