Top 15 Brian Kernighan Quotes (2025 Update)

1. “Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it.”

— Brian Kernighan

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2. “Don’t document bad code – rewrite it.”

— Brian Kernighan

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3. “Controlling complexity is the essence of computer programming.”

— Brian Kernighan

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4. “90% of the functionality delivered now is better than 100% delivered never.”

— Brian Kernighan

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5. “The most effective debugging tool is still careful thought, coupled with judiciously placed print statements.”

— Brian Kernighan

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6. “Programming is learned by writing programs.”

— Brian Kernighan

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7. “Believe the terrain, not the map.”

— Brian Kernighan

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8. “Mechanical rules are never a substitute for clarity of thought.”

— Brian Kernighan

9. “Do what you think is interesting, do something that you think is fun and worthwhile, because otherwise you won’t do it well anyway.”

— Brian Kernighan

10. “C is a razor-sharp tool, with which one can create an elegant and efficient program or a bloody mess.”

— Brian Kernighan

11. “An effective way to test code is to exercise it at its natural boundaries.”

— Brian Kernighan

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12. “Trying to outsmart a compiler defeats much of the purpose of using one.”

— Brian Kernighan

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13. “If you had done something twice, you are likely to do it again.”

— Brian Kernighan

14. “Each new user of a new system uncovers a new class of bugs.”

— Brian Kernighan

15. “Get the weirdnesses into the data where you can manipulate them easily, and the regularity into the code because regular code is a lot easier to work with.”

— Brian Kernighan

16. “If you’re as clever as you can be when you write it, how will you ever debug it?”

— Brian Kernighan

17. “Trivia rarely affect efficiency. Are all the machinations worth it, when their primary effect is to make the code less readable?”

— Brian Kernighan

18. “As we said in the preface to the first edition, C “wears well as one’s experience with it grows.” With a decade more experience, we still feel that way.”

— Brian Kernighan