Brian Kernighan Quotes

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.

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

Controlling complexity is the essence of computer programming.

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

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.

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

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

Don't document bad code - rewrite it.

... 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.

Believe the terrain, not the map

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

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

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.

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.

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

Some compilers allow a check during execution that subscripts do not exceed array dimensions. This is a help, but not sufficient. First, many programmers do not use such compilers because They're not efficient. (Presumably, this means that it is vital to get the wrong answers quickly.)

An effective way to test code is to exercise it at its natural boundaries

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

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