Best practices for resource management in Python - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to open a file safely using a context manager.

Python

with open('example.txt', [1]) as file:
    content = file.read()

Drag options to blanks, or click blank then click option'

A'r'

B'x'

C'a'

D'w'

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'w' or 'a' mode when only reading is needed.

The mode 'r' opens the file for reading, which is safe for reading content.

2fill in blank

medium

Complete the code to ensure a file is closed properly after writing.

Python

file = open('output.txt', [1])
file.write('Hello')
file.close()

Drag options to blanks, or click blank then click option'

A'w'

B'a'

C'x'

D'r'

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'r' mode when trying to write to a file.

The mode 'w' opens the file for writing and overwrites existing content.

3fill in blank

hard

Fix the error in the code to properly handle file opening with a context manager.

Python

file = open('data.txt', 'r')
with [1] as f:
    data = f.read()

Drag options to blanks, or click blank then click option'

Adata

Bopen('data.txt', 'r')

Cfile

Df

Attempts:

3 left

💡 Hint

Common Mistakes

Using open() again inside the with statement causing resource leaks.

The variable 'file' is already the opened file object and should be used in the with statement.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that stores file sizes for files larger than 1000 bytes.

Python

sizes = {filename: [1] for filename, size in files.items() if size [2] 1000}

Drag options to blanks, or click blank then click option'

Asize

B>

C<

Dfilename

Attempts:

3 left

💡 Hint

Common Mistakes

Using filename as value or wrong comparison operator.

The comprehension stores the size for each filename where the size is greater than 1000 bytes.

5fill in blank

hard

Fill all three blanks to create a safe file reading dictionary comprehension filtering files with '.txt' extension.

Python

file_contents = [1]: open([2], 'r').read() for [3] in filenames if [2].endswith('.txt')

Drag options to blanks, or click blank then click option'

Afilename

Dfile

Attempts:

3 left

💡 Hint

Common Mistakes

Using different variable names causing NameError.

The comprehension reads content from each file named 'filename' that ends with '.txt'.

Practice

1.

Why is it recommended to use the with statement when working with files in Python?

easy

A. It automatically closes the file after the block ends.

B. It makes the file open faster.

C. It prevents the file from being read.

D. It duplicates the file content.

Solution

1. Step 1: Understand the with statement role

   The with statement ensures that resources like files are properly closed after use, even if errors occur.

2. Step 2: Recognize automatic resource management

   Using with automatically calls the file's close() method when the block finishes.

3. Final Answer:

   It automatically closes the file after the block ends. -> Option A

4. Quick Check:

   with closes files automatically [OK]

Hint: Remember: with auto-closes resources [OK]

Common Mistakes:

• Thinking with speeds up file opening
• Believing with prevents reading
• Assuming with duplicates content

2.

Which of the following is the correct syntax to open a file named data.txt for reading using with?

?

easy

A. open with('data.txt', 'r') as file:

B. with open('data.txt') file:

C. with open('data.txt', 'r') as file:

D. with open('data.txt', 'read') as file:

Solution

1. Step 1: Recall correct open syntax

   The correct way to open a file for reading is open(filename, 'r').

2. Step 2: Check with statement syntax

   The with statement requires with open(...) as variable: format.

3. Final Answer:

   with open('data.txt', 'r') as file: -> Option C

4. Quick Check:

   Correct with open syntax = with open('data.txt', 'r') as file: [OK]

Hint: Use with open(filename, 'r') as var: [OK]

Common Mistakes:

• Omitting 'as' keyword
• Using 'read' instead of 'r' mode
• Wrong order of keywords

3.

What will be the output of this code?

with open('test.txt', 'w') as f:
    f.write('Hello')
print(f.closed)

medium

A. True

B. False

C. Hello

D. Error

Solution

1. Step 1: Understand with block effect on file

   The with block opens the file and closes it automatically after the block ends.

2. Step 2: Check f.closed after block

   Since the file is closed after the block, f.closed will be True.

3. Final Answer:

   True -> Option A

4. Quick Check:

   File closed after with block = True [OK]

Hint: File is closed after with block ends [OK]

Common Mistakes:

• Thinking file stays open after with
• Expecting file content printed
• Confusing f.closed value

4.

Find the error in this code snippet:

file = open('log.txt', 'w')
file.write('Start logging')
# forgot to close the file

medium

A. File is not opened in read mode.

B. File name should be a variable.

C. File write syntax is incorrect.

D. File is not closed after writing.

Solution

1. Step 1: Check file opening and writing

   The file is opened correctly in write mode and data is written properly.

2. Step 2: Identify missing resource management

   The file is not closed after writing, which can cause data loss or resource leaks.

3. Final Answer:

   File is not closed after writing. -> Option D

4. Quick Check:

   Always close files after use [OK]

Hint: Always close files or use with [OK]

Common Mistakes:

• Ignoring missing close() call
• Thinking write syntax is wrong
• Confusing file modes

5.

You want to read multiple files and combine their contents safely. Which approach is best?

?

hard

A. Open all files without with and close manually later.

B. Use nested with statements to open each file safely.

C. Open files with open() but never close them.

D. Read files using open() without closing or with.

Solution

1. Step 1: Consider resource safety when reading multiple files

   Opening multiple files requires careful closing to avoid leaks or errors.

2. Step 2: Use nested with statements

   Nested with ensures each file is opened and closed properly, even if errors occur.

3. Final Answer:

   Use nested with statements to open each file safely. -> Option B

4. Quick Check:

   Nested with = safe multi-file handling [OK]

Hint: Use nested with for multiple files [OK]

Common Mistakes:

• Not closing files manually
• Opening many files without with
• Ignoring errors during file operations