Why file handling is required in Python - Test Your Understanding

Practice - 5 Tasks

1fill in blank

easy

Complete the code to open a file named 'data.txt' for reading.

Python

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

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

Ar

Bw

Ca

Dx

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'w' or 'a' mode when you want to read a file.

To read a file, you open it with mode 'r'.

2fill in blank

medium

Complete the code to write the string 'Hello' to a file named 'output.txt'.

Python

with open('output.txt', '[1]') as f:
    f.write('Hello')

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

Ar

Bw

Ca

Dx

Attempts:

3 left

💡 Hint

Common Mistakes

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

Use mode 'w' to write to a file, which creates or overwrites it.

3fill in blank

hard

Fix the error in the code to read all lines from 'log.txt'.

Python

with open('log.txt', 'r') as f:
    lines = f.[1]()

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

Areadline

Bclose

Cwrite

Dreadlines

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'readline()' when all lines are needed.

The method 'readlines()' reads all lines into a list.

4fill in blank

hard

Fill both blanks to create a dictionary with words as keys and their lengths as values, only for words longer than 3 letters.

Python

words = ['apple', 'cat', 'banana', 'dog']
lengths = {word: [1] for word in words if len(word) [2] 3}

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

Alen(word)

B>

C<

Dword

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' in the condition.

Use len(word) to get length and '>' to filter words longer than 3 letters.

5fill in blank

hard

Fill all three blanks to create a dictionary with uppercase words as keys, their lengths as values, only for words longer than 4 letters.

Python

words = ['tree', 'house', 'car', 'elephant']
result = { [1]: [2] for w in words if len(w) [3] 4 }

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

Aw.upper()

Blen(w)

C>

Dw.lower()

Attempts:

3 left

💡 Hint

Common Mistakes

Using w.lower() instead of w.upper().

Using '<' instead of '>'.

Use w.upper() for keys, len(w) for values, and '>' to filter words longer than 4 letters.

Practice

1. Why do we need file handling in Python programs?

easy

A. To save data permanently so it can be used later

B. To make the program run faster

C. To change the color of the text on screen

D. To create graphics and animations

Solution

1. Step 1: Understand the purpose of file handling

   File handling allows programs to save data to files so it is not lost when the program stops.

2. Step 2: Identify the correct reason among options

   Only To save data permanently so it can be used later talks about saving data permanently, which matches the purpose of file handling.

3. Final Answer:

   To save data permanently so it can be used later -> Option A

4. Quick Check:

   File handling = save data permanently [OK]

Hint: File handling = saving/loading data outside program [OK]

Common Mistakes:

• Thinking file handling speeds up program
• Confusing file handling with graphics
• Believing file handling changes screen colors

2. Which of the following is the correct way to open a file named data.txt for reading in Python?

easy

A. open('data.txt', 'w')

B. open('data.txt', 'x')

C. open('data.txt', 'r')

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

Solution

1. Step 1: Recall file modes in Python

   'r' mode opens a file for reading, 'w' for writing, 'x' for creating, 'a' for appending.

2. Step 2: Match mode with reading requirement

   Since we want to read the file, 'r' mode is correct.

3. Final Answer:

   open('data.txt', 'r') -> Option C

4. Quick Check:

   Read mode = 'r' [OK]

Hint: Use 'r' mode to open files for reading [OK]

Common Mistakes:

• Using 'w' which overwrites file
• Using 'a' which appends instead of reading
• Confusing 'x' with reading mode

3. What will be the output of this code?

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

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

medium

A. Empty output

B. test.txt

C. Error: file not found

D. Hello

Solution

1. Step 1: Write 'Hello' to file 'test.txt'

   The first block opens 'test.txt' in write mode and writes 'Hello' inside it.

2. Step 2: Read and print the file content

   The second block opens the same file in read mode and prints its content, which is 'Hello'.

3. Final Answer:

   Hello -> Option D

4. Quick Check:

   Write then read = Hello [OK]

Hint: Write then read file prints written text [OK]

Common Mistakes:

• Expecting error because file exists
• Thinking file is empty after writing
• Confusing file name with content

4. Find the error in this code that tries to read a file:

f = open('info.txt', 'r')
print(f.read())
f.close()

medium

A. File 'info.txt' might not exist causing error

B. File mode should be 'w' instead of 'r'

C. Missing parentheses in print statement

D. File should be opened with 'a' mode

Solution

1. Step 1: Check file opening mode

   The code opens file in 'r' mode which is correct for reading.

2. Step 2: Consider file existence

   If 'info.txt' does not exist, opening in 'r' mode causes a FileNotFoundError.

3. Final Answer:

   File 'info.txt' might not exist causing error -> Option A

4. Quick Check:

   Reading missing file = error [OK]

Hint: Reading non-existent file causes error [OK]

Common Mistakes:

• Changing mode to 'w' which overwrites file
• Thinking print needs no parentheses in Python 3
• Using 'a' mode which is for appending, not reading

5. You want to save user settings so they are remembered next time the program runs. Which file handling approach is best?

hard

A. Store settings only in variables during program run

B. Write settings to a file and read them when program starts

C. Print settings on screen without saving

D. Use file mode 'x' to read settings

Solution

1. Step 1: Understand the need to remember data between runs

   Variables lose data when program ends, so saving to a file is needed.

2. Step 2: Choose correct file handling method

   Writing settings to a file and reading them later keeps data persistent.

3. Final Answer:

   Write settings to a file and read them when program starts -> Option B

4. Quick Check:

   Persistent data = save to file [OK]

Hint: Save to file to keep data after program ends [OK]

Common Mistakes:

• Thinking variables keep data after program closes
• Confusing file mode 'x' which creates new file
• Assuming printing saves data