Understanding your code

Do you completely understand every line of your code? Ask yourself if you could explain each line to a colleague. If not: Investigate.

Understanding your code means you should be able to explain every line to a colleague without hesitation. If you can’t, it’s a red flag. Writing code you don’t fully grasp leads to bugs, technical debt, and fragile systems. Every piece of code you commit should be intentional, not mysterious.

A practical way to apply this principle is the “rubber duck test”: explain your code aloud, line by line, as if a colleague - or even a rubber duck - is listening. If you stumble, refactor or add clarity. This ensures that code reviews are meaningful and maintenance is easier.

Example:

// Confusing: what does this do? magic numbers, unclear intent
double result = x * 0.453592;

// Clear: everyone understands the conversion
double poundsToKilograms(double pounds) {
    return pounds * 0.453592;
}

Notice how the second version is self-explanatory. Anyone reading it immediately understands the purpose, without needing a comment.

Another tip: use descriptive names, extract methods for complex logic, and avoid clever hacks that only you understand. Complex operations should live in well-named methods that document intent:

// Hard to understand in-place
if ((balance - withdrawal) < 0) { ... }

// Clear and intentional
if (wouldOverdraft(balance, withdrawal)) { ... }

Before each commit, ask yourself: “Could a teammate understand this without asking me?” If the answer is no, stop, clarify, refactor. This habit prevents technical debt from sneaking in, improves collaboration, and builds a codebase that is resilient and maintainable. Clear understanding is the foundation of clean, professional code.