Lesson 3: C++ toolchain and basics: Debugging scenario

Concept Explanation

In this lesson, you practice debugging a small C++ program that fails in a predictable way. The point is not just to see an error message. The point is to follow the flow: identify what the code is trying to do, reproduce the issue, and then improve the program so the behavior is easier to understand. This is a beginner-friendly debugging habit that will matter later when your programs become larger and the source of a problem is less obvious.

Where to Put the Code

1. Start with variables and inputs. Keep includes, main function, and data types explicit.
2. Add processing logic in the middle section.
3. Finish with output and quick validation.

Command Reference

• Run the program and confirm which input causes the failure path.
• Change the values in `divideItems` to test one working case and one failing case.
• Keep the throw site and the catch block easy to read so the error path is obvious.
• Describe one debugging choice that made the program easier to inspect.

Step-by-step Guide

1. Build and run the example exactly as written to observe the handled error.
2. Identify why `divideItems(12, 0)` cannot succeed.
3. Change the second argument to a valid number and compare the new output.
4. Add or edit one message so the failure case is clearer to a user reading the terminal.
5. Summarize in one sentence how the `try` and `catch` blocks help during debugging.

Practice Exercises

• Add a second test call with a valid divisor and print both results clearly.
• Rewrite the example so the function checks for another bad input such as negative boxes.
• Create a small report in `main` that shows whether each test case passed or failed.

Coding Challenges

• Implement the same scenario once with direct checks and once with an exception, then compare readability.
• Refactor the code so the calculation logic and the user-facing messages are separated cleanly.

Mini Practice Tasks

• Rename one variable so the intention of the code is easier to follow.
• Add one extra guarded case and rerun the program.
• Write a one-line summary of the bug this lesson is designed to expose.