3.6.3 Debugging Techniques and Tools

Imagine you've built your LEGO castle, but one tower keeps falling over. You know there's a problem, but you don't know exactly why or where! You need to become a detective.

Debugging is the process of finding and fixing errors (bugs) in your computer program. It's a skill every programmer develops, and it often takes more time than writing the code itself!

Here are some common techniques and tools used for debugging:

1. Print Statements (The Simplest Tool):
- Technique: This is often the first thing programmers do. You strategically add print() (or System.out.println() in Java) statements throughout your code to display the values of variables or messages at different points.
- Purpose: To see what your program is doing step-by-step and what values your variables hold at certain moments. This helps you pinpoint where things start to go wrong.

Example:

num1 = 5

num2 = 10

print(f"Before calculation: num1={num1}, num2={num2}") # Print statement

sum = num1 + num2

print(f"After calculation: sum={sum}") # Another print statement

2. Code Review (Looking for Mistakes):
- Technique: Carefully read through your code, line by line, as if you were the computer executing it. Try to spot any logical mistakes or typos.
- Purpose: Sometimes, just looking at the code with fresh eyes (or having a friend look at it) can reveal simple errors.
3. Debuggers (The Detective's Super Tool):
- Tool: A debugger is a special software tool (often built into your Integrated Development Environment or IDE, like VS Code, Eclipse, IntelliJ, PyCharm).
- Purpose: Debuggers let you control your program's execution like a remote control:
  - Breakpoints: You can set "breakpoints" on specific lines of code. When the program runs and reaches a breakpoint, it pauses.
  - Step-by-Step Execution: You can then execute your code one line at a time ("step over" or "step into") to see exactly what happens at each step.
  - Inspect Variables: While paused, you can look at the current values of all your variables, which is incredibly helpful for finding logic errors.
  - Call Stack: You can see which functions called which, helping you understand the flow of your program.
- How to use: Learning to use a debugger is one of the most valuable skills for any programmer. It makes finding complex bugs much faster than just using print statements.
4. Error Messages and Logs:
- Technique: When your program crashes with a runtime error, it usually provides an error message (like the one you saw with MediaWiki) and a "stack trace" (a list of function calls leading up to the error).
- Purpose: These messages are clues! They tell you the type of error and often the exact line number where it happened.
- How to use: Read them carefully. Even if they look confusing at first, the line numbers are usually the most helpful place to start investigating.

Debugging is a fundamental part of programming. It teaches you patience, attention to detail, and problem-solving skills that are useful in many areas of life!

Bibliography:

W3Schools - Debugging in C: https://www.w3schools.com/c/c_debugging.php
GeeksforGeeks - Python Debugging: https://www.geeksforgeeks.org/python/working-with-the-python-debugger/
Wikipedia - Debugging: https://en.wikipedia.org/wiki/Debugging