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

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

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.

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

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

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.