C programming tricks

While programming optimization that makes ones' code completely unreadable is often a bad thing, there are places for it, like that one inner loop of your code that takes up 98% of the program's running time.

What are you tricks for improving performance in C, other than the obvious inline assembly or the like?

>>127
the way you interpret that second sentence, if(i++) would be invalid because i is modified and it's prior value is read for a purpose other than determining the value to be stored. this is obviously not what the authors of the standard intended.