Debugging mindset in Intro to Computing - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to print the error message when an exception occurs.

Intro to Computing

try:
    result = 10 / 0
except ZeroDivisionError as [1]:
    print([1])

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

Ae

Berror

Cexception

Derr

Attempts:

3 left

💡 Hint

Common Mistakes

Using a variable name not matching the print statement.

Forgetting to use 'as' keyword.

In Python, the common variable name to catch an exception is e. This variable holds the error message.

2fill in blank

medium

Complete the code to check if a number is positive and print a message.

Intro to Computing

number = -5
if number [1] 0:
    print("Positive number")
else:
    print("Not positive")

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

A>=

B<

C==

D>

Attempts:

3 left

💡 Hint

Common Mistakes

Using '<' instead of '>' causing wrong output.

Using '==' which only checks equality.

The condition number > 0 checks if the number is positive.

3fill in blank

hard

Fix the error in the code to correctly access the first element of the list.

Intro to Computing

my_list = [10, 20, 30]
first_element = my_list[1]

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

A(0)

B[0]

C{0}

D<0>

Attempts:

3 left

💡 Hint

Common Mistakes

Using parentheses which call a function.

Using curly braces which define sets or dictionaries.

In Python, list elements are accessed using square brackets [] with the index inside.

4fill in blank

hard

Fill both blanks to create a dictionary comprehension that maps words to their lengths only if length is greater than 3.

Intro to Computing

{word: [1] for word in words if [2]

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

Alen(word)

Bword

Clen(word) > 3

Dword > 3

Attempts:

3 left

💡 Hint

Common Mistakes

Using the word itself as the value instead of its length.

Comparing the word string directly to a number.

The dictionary comprehension maps each word to its length using len(word). The condition len(word) > 3 filters words longer than 3 characters.

5fill in blank

hard

Fill all three blanks to create a dictionary comprehension that maps uppercase words to their lengths if length is greater than 2.

Intro to Computing

{ [1]: [2] for word in words if [3] }

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

Aword.upper()

Blen(word)

Clen(word) > 2

Dword.lower()

Attempts:

3 left

💡 Hint

Common Mistakes

Using word.lower() instead of uppercase.

Not filtering words by length correctly.

The comprehension maps the uppercase version of each word (word.upper()) to its length (len(word)) only if the length is greater than 2 (len(word) > 2).

Practice

1. What is the main goal of having a debugging mindset when working with code?

easy

A. To ignore error messages and keep coding

B. To write code as fast as possible without testing

C. To carefully check and fix code step-by-step

D. To copy code from others without understanding

Solution

1. Step 1: Understand the purpose of debugging mindset

   Debugging mindset means being careful and systematic in finding and fixing errors in code.

2. Step 2: Compare options with this purpose

   Only To carefully check and fix code step-by-step matches this careful step-by-step checking and fixing approach.

3. Final Answer:

   To carefully check and fix code step-by-step -> Option C

4. Quick Check:

   Debugging mindset = careful step-by-step fixing [OK]

Hint: Debugging means careful step-by-step checking [OK]

Common Mistakes:

• Thinking debugging is about coding fast
• Ignoring error messages
• Copying code without understanding

2. Which of the following is the correct way to write a comment in Python to help with debugging?

easy

A.

B. # This is a comment

C. /* This is a comment */

D. // This is a comment

Solution

1. Step 1: Identify Python comment syntax

   Python uses the # symbol to start a comment line.

2. Step 2: Match options with Python syntax

   # This is a comment uses #, which is correct. Others are comment styles for HTML, JavaScript, or C.

3. Final Answer:

   # This is a comment -> Option B

4. Quick Check:

   Python comment = # [OK]

Hint: Python comments start with # symbol [OK]

Common Mistakes:

• Using // or /* */ which are not Python comments
• Using HTML comment syntax in Python

3. Consider this Python code snippet:

def add_numbers(a, b):
    return a + b

result = add_numbers(3, '4')
print(result)

What will happen when this code runs?

medium

A. It raises a TypeError

B. It prints 34

C. It prints 7

D. It prints null

Solution

1. Step 1: Analyze the function call with mixed types

   The function tries to add an integer 3 and a string '4'.

2. Step 2: Understand Python's behavior on adding int and str

   Python cannot add int and str directly, so it raises a TypeError.

3. Final Answer:

   It raises a TypeError -> Option A

4. Quick Check:

   int + str = TypeError [OK]

Hint: Adding int and str causes TypeError in Python [OK]

Common Mistakes:

• Thinking Python concatenates int and str
• Expecting numeric addition without type conversion

4. You have this JavaScript code:

let count = 0;
for(let i = 0; i < 5; i++) {
  count = count + i;
}
console.log(count);

But the output is always 0. What is the most likely error?

medium

A. The console.log statement is missing

B. The loop condition is wrong, it never runs

C. The variable count is declared with let outside the loop

D. The variable count is reset inside the loop

Solution

1. Step 1: Check where count is updated

   If count is reset to 0 inside the loop each time, it never accumulates.

2. Step 2: Identify the cause of output always 0

   Resetting count inside the loop causes it to stay 0 after loop ends.

3. Final Answer:

   The variable count is reset inside the loop -> Option D

4. Quick Check:

   Resetting accumulator inside loop = no sum [OK]

Hint: Check if accumulator resets inside loop [OK]

Common Mistakes:

• Assuming loop never runs
• Ignoring variable reset inside loop
• Thinking console.log missing causes no output

5. You want to debug a program that processes a list of numbers but sometimes skips numbers unexpectedly. Which approach best uses a debugging mindset to find the problem?

hard

A. Add print statements inside the loop to trace each number processed

B. Delete the entire code and rewrite it from scratch

C. Ignore the problem and hope it fixes itself

D. Change random parts of the code without testing

Solution

1. Step 1: Choose a systematic way to observe program behavior

   Adding print statements inside the loop helps see which numbers are processed.

2. Step 2: Use this information to identify where skipping happens

   Tracing output step-by-step reveals logic errors causing skips.

3. Final Answer:

   Add print statements inside the loop to trace each number processed -> Option A

4. Quick Check:

   Trace program flow step-by-step to debug [OK]

Hint: Trace code step-by-step with print statements [OK]

Common Mistakes:

• Rewriting code without understanding
• Ignoring errors
• Changing code randomly without testing