Computer Science I / Integrated Introductory Programming Practice
Practice question · Multiple choice

A beginner writes a working program and cannot explain why it works. Why is that a problem even though the tests pass?

Hints
  1. Ask what happens the first time the program must be changed.
  2. Understanding is what lets you predict. Predict what?
Show the answer

D. Because they cannot predict what will break it

Why

Working is a snapshot; understanding is what lets you predict behaviour under change. Without it, the first modification or unusual input produces a failure with no model to reason from, which is why tracing by hand and explaining code aloud are skills worth practising deliberately.

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