Learning Objectives / Whāinga Ako

• Define what "debugging" means in digital technologies.

• Explain why debugging is an essential part of creating and maintaining digital outcomes.

• Identify common types of errors (bugs) that occur in programs or systems.

• Describe basic strategies and tools used for debugging.

• Understand that debugging is an iterative process.

Getting Started / Whakataki (Prior Knowledge Required)

To get the most out of learning about Debugging, it's essential to have a clear understanding of:

• Sequence: Do you know that the order of instructions is critical, and a wrong order can cause issues? (Link to Sequence page)

• Algorithms: Do you understand that algorithms are step-by-step instructions for solving problems? (Link to Algorithms page)

• Computer Program: Are you familiar with programs as algorithms translated into code for computers to execute? (Link to Computer Program page)

Quick Check: Have you ever followed a recipe but something went wrong (e.g., the cake didn't rise, or the food tasted off)? How did you try to figure out what happened? That's a form of debugging!

What is Debugging?

Debugging is the process of finding and fixing errors, often called "bugs," in computer programs, algorithms, or digital systems. These "bugs" are flaws that cause the system to produce incorrect or unexpected results, or to stop working entirely.

The term "bug" supposedly originated in the 1940s when a moth (a literal bug) got trapped in a relay of an early computer, causing it to malfunction. Today, a "bug" almost always refers to an error in the code or design, not a real insect!

Debugging is an essential skill for anyone who creates or works with digital technologies because:

• It's very rare to write a perfect computer program or design a flawless system on the first try.

• Even a tiny mistake in a sequence of instructions can lead to major problems.

• You need to identify where the error is, understand why it's happening, and then figure out how to fix it.

How It Works / Me Pēhea te Mahi

Debugging is often an iterative process, meaning you might go through the steps multiple times until all errors are resolved.

Here's a common approach to debugging:

1. Can you make the error happen again? If you can reliably reproduce it, you can study it.

2. Where exactly is the error happening? This involves narrowing down the code or part of the system that seems to be causing the issue.

   • Check the sequence: Is an instruction out of order?

   • Check inputs: Is the system getting the wrong information?

   • Check logic: Is a selection rule or an iteration loop behaving unexpectedly?

3. Why is the bug occurring? What specific instruction or condition is creating the problem?

4. Change the code or adjust the system to correct the error.

5. Run the program/system again to confirm the bug is gone and that no new bugs have been introduced. This ties directly into the Testing concept (Link to Testing page).

Common Debugging Strategies:

• Manually go through the algorithm or code step-by-step, imagining what the computer is doing at each point, keeping track of variables and outputs.

• Adding temporary commands to your program (e.g., PRINT statements) to display the value of variables or indicate which parts of the code are being executed. This helps you "see inside" the program.

• Many programming environments have special tools called "debuggers" that let you pause your program, run it line-by-line, and inspect the values of variables as it runs.

• If a large program has a bug, try to create a smaller, simpler version of the program that still shows the bug. This makes it easier to isolate.

• Sometimes the bug is not in the code, but in your understanding of how a part of the system works. Re-read documentation or re-evaluate your assumptions.

Debugging can be frustrating, but it's also a powerful way to learn. Each bug you fix improves your understanding of how digital systems work.

Assessment / Te Aromatawai

Check your understanding of Debugging.

1. Multiple Choice: What is the primary purpose of debugging?

   • a) To make a computer program run faster.

   • b) To hide secrets in a program.

   • c) To find and fix errors in software or algorithms.

   • d) To design the visual appearance of a program.

2. Short Answer: Why is it unlikely that a programmer will write a complex computer program without needing to debug it?

3. Scenario: You are trying to use a new application that sorts a list of names alphabetically. When you run it, it always puts names starting with 'Z' at the beginning of the list, which is incorrect.

   • What type of error or "bug" is this (e.g., a spelling mistake, a logic error, a sequence error)?

   • Name one specific debugging strategy you could use to try and find why the 'Z' names are appearing first.

Key Takeaways / Mātauranga

• Debugging (whakatika hapa) is the process of finding and fixing "bugs" (errors) in computer programs and digital systems.

• Bugs cause unexpected or incorrect behaviour.

• Debugging is an essential, iterative process involving reproducing, isolating, understanding, fixing, and testing.

• Common strategies include tracing, using print statements, and using special debugger tools.

• Fixing bugs improves your understanding and the quality of digital outcomes.

What's Next?

Now that you understand how to find and fix errors, you're ready to explore another critical aspect of quality assurance in digital technologies:

• Testing: Learn how testing goes hand-in-hand with debugging, systematically checking if a program or system works correctly and meets its requirements. (This is often the next step after a bug is fixed!)

• Computer Program: Apply your debugging skills as you learn more about writing and developing complex programs.

• Design Process (Iterative Development): See how debugging fits into the larger cycle of designing, building, and refining digital solutions.

Continue your journey by clicking on the links to these exciting topics!