Bug tracking and fixing in Intro to Computing - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ trace

intermediate

Trace the output of a simple loop with a bug

What will be the output of the following code snippet?

Intro to Computing

numbers = [1, 2, 3, 4]
result = 0
for num in numbers:
    result += num
print(result)

A SyntaxError

B 0

C TypeError

D 10

💡 Hint

Think about what the loop does to the result variable.

The loop adds each number in the list to result. The sum of 1+2+3+4 is 10.

❓ identification

intermediate

Identify the type of error in a code snippet

What type of error will the following code produce?

Intro to Computing

def greet(name):
    print('Hello, ' + name)
greet()

A IndentationError

B NameError

C TypeError

D SyntaxError

💡 Hint

Check the function call and its parameters.

The function greet requires one argument, but it is called without any, causing a TypeError.

🧠 Conceptual

advanced

Understanding the debugging process

Which step is not part of the typical debugging process?

A Writing new unrelated features

B Isolating the cause

C Identifying the problem

D Testing the fix

💡 Hint

Think about what debugging focuses on.

Debugging focuses on finding and fixing problems, not adding new unrelated features.

❓ Comparison

advanced

Compare error types in code snippets

Which code snippet will cause a SyntaxError?

A

x = 10
print(x)

B if x == 5 print('Yes')

C

for i in range(3):
    print(i)

D print('Hello' + 'World')

💡 Hint

Look for missing punctuation or structure errors.

Option B is missing a colon after the if statement, causing a SyntaxError.

🚀 Application

expert

Find the output after fixing a bug in code

After fixing the bug in the code below, what will be the output?

Intro to Computing

def calculate_area(radius):
    area = 3.14 * radius ** 2
    return area

result = calculate_area(5)
print(result)

A 78.5

B SyntaxError

C TypeError

D None

💡 Hint

Check the formula and the function return.

The function correctly calculates the area of a circle with radius 5: 3.14 * 5^2 = 78.5.

Practice

1. What is the main purpose of bug tracking in software development?

easy

A. To find and fix errors in the software

B. To add new features to the software

C. To design the user interface

D. To write documentation for users

Solution

1. Step 1: Understand the role of bug tracking

   Bug tracking is used to identify and keep track of errors or problems in software.

2. Step 2: Differentiate from other tasks

   Adding features, designing UI, and writing documentation are separate tasks from bug tracking.

3. Final Answer:

   To find and fix errors in the software -> Option A

4. Quick Check:

   Bug tracking = find and fix errors [OK]

Hint: Bug tracking = finding and fixing errors [OK]

Common Mistakes:

• Confusing bug tracking with adding features
• Thinking bug tracking is for UI design
• Mixing bug tracking with writing documentation

2. Which of the following is the correct way to report a bug?

easy

A. The app crashes when I click the 'Save' button. Steps to reproduce: 1. Open app 2. Click 'Save' 3. Observe crash.

B. The app is bad and doesn't work.

C. Fix the bug in the code immediately.

D. Add more features to the app.

Solution

1. Step 1: Identify a good bug report

   A good bug report clearly describes the problem and how to reproduce it.

2. Step 2: Compare options

   The app crashes when I click the 'Save' button. Steps to reproduce: 1. Open app 2. Click 'Save' 3. Observe crash. gives clear steps and describes the crash. Other options are vague or unrelated.

3. Final Answer:

   The app crashes when I click the 'Save' button. Steps to reproduce: 1. Open app 2. Click 'Save' 3. Observe crash. -> Option A

4. Quick Check:

   Clear bug report = detailed steps [OK]

Hint: Good bug reports include clear steps to reproduce [OK]

Common Mistakes:

• Writing vague bug descriptions
• Confusing bug reporting with fixing
• Reporting unrelated feature requests as bugs

3. Consider this code snippet that causes a bug:

def divide(a, b):
    return a / b

result = divide(10, 0)
print(result)

What will happen when this code runs?

medium

A. It will print 10

B. It will cause a runtime error (division by zero)

C. It will print 0

D. It will print None

Solution

1. Step 1: Analyze the divide function call

   The function tries to divide 10 by 0, which is mathematically undefined.

2. Step 2: Understand Python's behavior on division by zero

   Python raises a ZeroDivisionError at runtime when dividing by zero.

3. Final Answer:

   It will cause a runtime error (division by zero) -> Option B

4. Quick Check:

   Division by zero = runtime error [OK]

Hint: Division by zero causes runtime error in Python [OK]

Common Mistakes:

• Assuming division by zero returns 0
• Thinking it returns None
• Expecting the program to continue without error

4. You have this buggy code:

def find_max(numbers):
    max_num = 0
    for num in numbers:
        if num > max_num:
            max_num = num
    return max_num

print(find_max([-5, -2, -10]))

What is the bug and how to fix it?

medium

A. Remove the for loop

B. Change '>' to '<' in the if condition

C. Return min_num instead of max_num

D. Initialize max_num to first list element instead of 0

Solution

1. Step 1: Understand the bug with negative numbers

   Initializing max_num to 0 causes wrong result when all numbers are negative because 0 is greater than all negatives.

2. Step 2: Fix by initializing max_num to first element

   Set max_num = numbers[0] so comparison starts correctly with actual list values.

3. Final Answer:

   Initialize max_num to first list element instead of 0 -> Option D

4. Quick Check:

   Start max_num with first element for correct max [OK]

Hint: Initialize max with first list item, not zero [OK]

Common Mistakes:

• Assuming zero is always smallest
• Changing comparison direction incorrectly
• Removing loop instead of fixing initialization

5. A team uses a bug tracking tool to manage issues. They notice some bugs are marked 'fixed' but reappear later. What is the best way to prevent this?

hard

A. Assign bugs to multiple developers at once

B. Ignore bugs that reappear after fixing

C. Add thorough testing and verify fixes before closing bugs

D. Close bugs immediately after code change

Solution

1. Step 1: Understand why bugs reappear

   Bugs reappear if fixes are not properly tested or verified before closing.

2. Step 2: Implement thorough testing and verification

   Testing ensures the bug is truly fixed and prevents regression.

3. Final Answer:

   Add thorough testing and verify fixes before closing bugs -> Option C

4. Quick Check:

   Test fixes before closing bugs to prevent reappearance [OK]

Hint: Test fixes carefully before closing bugs [OK]

Common Mistakes:

• Closing bugs without testing
• Ignoring recurring bugs
• Assigning bugs to many developers causing confusion