46 Quotes by Brian Kernighan

If you're as clever as you can be when you write it, how will you ever debug it?

Mechanical rules are never a substitute for clarity of thought.

Believe the terrain, not the map

Each new user of a new system uncovers a new class of bugs.

Another effective [debugging] technique is to explain your code to someone else. This will often cause you to explain the bug to yourself. Sometimes it takes no more than a few sentences, followed by an embarrassed "Never mind, I see what's wrong. Sorry to bother you." This works remarkably well; you can even use non-programmers as listeners. One university computer center kept a teddy bear near the help desk. Students with mysterious bugs were required to explain them to the bear before they could speak to a human counselor.

... it is a fundamental principle of testing that you must know in advance the answer each test case is supposed to produce. If you don't, you are not testing; you are experimenting.

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

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

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