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About this quote

What does it mean?
Proving code correct is not enough; testing it is also required.
In plain terms
Just because code is proven does not mean it works.
What can you take from it?
Always test your code after proving it.

Where it applies

  • software development
  • engineering
  • debugging

Putting it to work

  • run tests
  • verify logic
  • check edge cases

Questions to consider

  • How do you verify code?
  • Is proof enough?

Another view

Testing cannot catch every possible bug.

More from Donald Knuth

  1. Premature optimization is the root of all evil (or at least most of it) in programming.

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  2. I can't be as confident about computer science as I can about biology. Biology easily has 500 years of exciting problems to work on. It's at that level.

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  3. The psychological profiling [of a programmer] is mostly the ability to shift levels of abstraction, from low level to high level. To see something in the small…

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