Opening & Closing Files0%
Opening & Closing Files
Beginner8 min read•Updated: 2026-09-03
Opening & Closing Files
File handling allows Python scripts to read from and write to permanent storage on disk.
Key Concepts & Detailed Explanation
Common file modes:
- 'r' (Read): Default mode. Opens file for reading; raises FileNotFoundError if missing.
- 'w' (Write): Opens for writing. OVERWRITES existing contents; creates file if missing.
- 'a' (Append): Opens for writing. Appends data to end of file without overwriting.
- 'x' (Exclusive creation): Creates new file; fails if file already exists.
- 'b' (Binary): Used for images, audio, PDFs (e.g. 'rb', 'wb').
- 't' (Text): Default text mode.
Code Examples & Output
Python
# Basic file writing and manual closing
file = open("sample.txt", "w")
file.write("Welcome to MSK Institute File Handling Tutorial!\n")
file.write("Learning Python from scratch.\n")
file.close()
# Reading it back
file = open("sample.txt", "r")
content = file.read()
print("File content:\n" + content)
file.close()
Expected Output:
Output
File content:
Welcome to MSK Institute File Handling Tutorial!
Learning Python from scratch.
Best Practices & Common Pitfalls
Always close files to release OS file locks and prevent memory leaks. Better yet, use the 'with' statement.
Practice Quiz
1. Which file mode opens a file for writing and appends new content to the end without truncating?
- A) 'w'
- B) 'r'
- C) 'a'
- D) 'x'
Answer: C
Explanation: 'a' (append) mode appends to the end of the file.
2. What happens if you open a non-existent file in 'r' mode?
- A) Python creates an empty file
- B) Raises FileNotFoundError
- C) Returns None
- D) Raises PermissionError
Answer: B
Explanation: Reading a non-existent file raises FileNotFoundError.
Practice Challenge
Create a script that opens a file in 'a' mode and appends a timestamped log entry.
Next Lesson
Reading & Writing Files
Continue learning with hands-on practice, examples, and exercises in the upcoming topic.
Related Lessons
| Previous Lesson | Next Lesson |
|---|---|
| Project: Calculator | Reading & Writing Files |
Practice Quiz
Test your understanding of this lesson with 1 questions. Each question has one correct answer.