Appending data to files in Python - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to open a file named 'log.txt' in append mode.

Python

file = open('log.txt', '[1]')

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

Ar

Ba

Cw

Dx

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'w' mode which overwrites the file.

Using 'r' mode which is read-only.

To add data to the end of a file without deleting existing content, use mode 'a' for append.

2fill in blank

medium

Complete the code to write the string 'Hello\n' to the file object named 'file'.

Python

file.[1]('Hello\n')

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

Awrite

Bread

Cappend

Dopen

Attempts:

3 left

💡 Hint

Common Mistakes

Trying to use a method named 'append' which does not exist.

Using 'read' which is for reading, not writing.

The write method adds text to the file.

3fill in blank

hard

Fix the error in the code to properly close the file after writing.

Python

file = open('log.txt', 'a')
file.write('Data\n')
file.[1]()

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

Aopen

Bflush

Cclose

Dwrite

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'flush' instead of 'close' which does not close the file.

Calling 'open' again instead of closing.

Always close a file after writing to save changes and free resources.

4fill in blank

hard

Fill both blanks to append the number 5 as a string to the file 'numbers.txt'.

Python

with open('numbers.txt', '[1]') as f:
    f.[2]('5\n')

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

Aa

Bw

Cwrite

Dappend

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'w' mode which overwrites the file.

Trying to use a method named 'append' which does not exist.

Open the file in append mode 'a' and use the write method to add text.

5fill in blank

hard

Fill all three blanks to append squares of numbers 1 to 3 to 'squares.txt', each on a new line.

Python

with open('squares.txt', '[1]') as f:
    for i in range(1, 4):
        f.[2](str(i[3]2) + '\n')

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

Aa

Bwrite

C**

D*

Attempts:

3 left

💡 Hint

Common Mistakes

Using '*' instead of '**' for exponentiation.

Using 'w' mode which overwrites the file.

Open in append mode 'a', use write to add text, and use '**' to square the number.

Practice

1. What does opening a file with mode 'a' in Python do?

easy

A. It opens the file for reading only.

B. It opens the file and deletes all existing content before writing.

C. It opens the file to add new data at the end without deleting existing content.

D. It creates a new file and writes data only if the file does not exist.

Solution

1. Step 1: Understand file modes in Python

   Mode 'a' stands for append mode, which means adding data at the end of the file.

2. Step 2: Compare with other modes

   Unlike 'w' mode which overwrites, 'a' keeps old data and adds new data after it.

3. Final Answer:

   It opens the file to add new data at the end without deleting existing content. -> Option C

4. Quick Check:

   Append mode = add data at end [OK]

Hint: Append mode 'a' adds data without erasing old content [OK]

Common Mistakes:

• Confusing 'a' with 'w' which overwrites file
• Thinking 'a' opens file for reading only
• Assuming 'a' creates a new file only if missing

2. Which of the following is the correct syntax to open a file named log.txt for appending text data?

easy

A. open('log.txt', 'x')

B. open('log.txt', 'r')

C. open('log.txt', 'w')

D. open('log.txt', 'a')

Solution

1. Step 1: Identify the mode for appending

   The mode 'a' is used to open a file for appending data.

2. Step 2: Check other modes

   'r' is for reading, 'w' is for writing (overwrites), 'x' is for exclusive creation.

3. Final Answer:

   open('log.txt', 'a') -> Option D

4. Quick Check:

   Append mode syntax = open(filename, 'a') [OK]

Hint: Use 'a' mode to append, not 'r', 'w', or 'x' [OK]

Common Mistakes:

• Using 'w' which erases file content
• Using 'r' which does not allow writing
• Using 'x' which fails if file exists

3. What will be the output of the following code if data.txt initially contains Hello?

with open('data.txt', 'a') as f:
    f.write(' World')

with open('data.txt', 'r') as f:
    print(f.read())

medium

A. Hello World

B. World

C. Hello

D. Hello\nWorld

Solution

1. Step 1: Understand the append operation

   The code opens 'data.txt' in append mode and adds ' World' after existing content 'Hello'.

2. Step 2: Read the updated file content

   Reading the file shows 'Hello World' as the new content without a newline.

3. Final Answer:

   Hello World -> Option A

4. Quick Check:

   Appending adds text at end without newline [OK]

Hint: Appending adds text exactly where file ends, no newline added [OK]

Common Mistakes:

• Expecting a newline between 'Hello' and 'World'
• Thinking append overwrites existing content
• Confusing output with just 'World'

4. The following code is intended to append a new line to notes.txt. What is the error?

with open('notes.txt', 'a') as file:
    file.write('New note')
    file.write('\n')

medium

A. The write method cannot be called twice on the same file object.

B. No error; code appends 'New note' and a newline correctly.

C. The file should be opened in 'w' mode to append data.

D. The newline character should be '\\r\\n' for Windows compatibility.

Solution

1. Step 1: Check file mode and write calls

   The file is opened in append mode 'a', which is correct for adding data.

2. Step 2: Verify writing multiple times

   Calling write twice is allowed; first writes 'New note', second writes a newline '\n'.

3. Final Answer:

   No error; code appends 'New note' and a newline correctly. -> Option B

4. Quick Check:

   Multiple writes in append mode work fine [OK]

Hint: Multiple writes allowed; 'a' mode appends safely [OK]

Common Mistakes:

• Thinking 'w' mode is needed to append
• Believing write() can be called only once
• Confusing newline characters for error

5. You want to append multiple lines from a list lines = ['First line', 'Second line', 'Third line'] to a file output.txt, each on a new line. Which code correctly does this?

hard

A. with open('output.txt', 'a') as f:
for line in lines:
f.write(line + '\n')

B. with open('output.txt', 'w') as f:
for line in lines:
f.write(line + '\n')

C. with open('output.txt', 'a') as f:
f.write(lines)

D. with open('output.txt', 'a') as f:
f.writelines(lines)

Solution

1. Step 1: Choose correct mode for appending

   Mode 'a' appends data without erasing existing content; 'w' overwrites.

2. Step 2: Write each line with newline

   Looping over lines and writing each with '\n' ensures each line is on a new line.

3. Step 3: Check other options

   with open('output.txt', 'a') as f: f.write(lines) tries to write list directly (error), writelines(lines) writes lines without newlines, the 'w' mode option overwrites file.

4. Final Answer:

   with open('output.txt', 'a') as f: for line in lines: f.write(line + '\n') -> Option A

5. Quick Check:

   Append mode + loop + add '\n' = correct [OK]

Hint: Loop and add '\n' when appending multiple lines [OK]

Common Mistakes:

• Using 'w' mode which erases file
• Writing list directly causing TypeError
• Using writelines() without newlines