programming maxims

Rob Pike offers the following "rules" in Notes on Programming in C as programming maxims, though they can be easily viewed as points of a Unix philosophy:^{[citation needed]}

• Rule 1: You cannot tell where a program is going to spend its time. Bottlenecks occur in surprising places, so do not try to second guess and put in a speed hack until you've proven that's where the bottleneck is.
• Rule 2: Measure. Do not tune for speed until you have measured, and even then don't unless one part of the code overwhelms the rest.
• Rule 3: Fancy algorithms are slow when n is small, and n is usually small. Fancy algorithms have big constants. Until you know that n is frequently going to be big, don't get fancy. (Even if n does get big, use Rule 2 first.)
• Rule 4: Fancy algorithms are buggier than simple ones, and they are much harder to implement. Use simple algorithms as well as simple data structures.
• Rule 5: Data dominates. If you have chosen the right data structures and organized things well, the algorithms will almost always be self-evident. Data structures, not algorithms, are central to programming.
• Rule 6: There is no Rule 6.

Pike's rules 1 and 2 restate C. A. R. Hoare's famous maxim "Premature optimization is the root of all evil." Ken Thompson rephrased Pike's rules 3 and 4 as "When in doubt, use brute force." Rules 3 and 4 are instances of the design philosophy KISS. Rule 5 was previously stated by Fred Brooks in The Mythical Man-Month. Jon Bentley's Programming Pearls also has a chapter on the same design principle. Rule 5 is often shortened to "write stupid code that uses smart data", and is an instance of the guideline "If your datastructures are good enough, the algorithm to manipulate them should be trivial." Rule 6 is merely a humorous reference to Monty Python's Bruces sketch. In C strings, the last byte of the string is null, thus indicating the length of the string.

ps: Taken from wikipedia http://en.wikipedia.org/wiki/Unix_philosophy