quoted from http://liw.fi/programming-truths/
Originally written in 1995.
This page contains a number of important programming truths that every budding programmer should know about. These truths are self-evident, and need no explanations.
If it compiles, it works.
If it compiles, it’s correct.
If it runs, it doesn’t have any bugs.
If it doesn’t have any immediately obvious bugs, it’s perfect.
If a bug doesn’t show, it doesn’t exist.
If it seems to work, it works.
Doing something right is easy. Avoiding errors only takes a bit of concentration.
The shorter the source code, the faster the program.
It’s obvious how to optimize a program.
Prorammers don’t make mistakes.