alt Hacker NewsFor the uninformed: counting backwards in a for loop is faster because comparing an unsigned integer against 0 is generally faster than comparing it against any other value.
It also says not to use `for (i >= 0)` because any unsigned integer is >= 0, and the loop will never end.
Replies
> ...counting backwards in a for loop is faster...
Maybe in 1990 ;)
(it's one of many cargo cult wisdom snippets that have become mostly obsolete once C compilers got proper optimizer passes and CPUs got all sorts of pipeling tricks)
> For the uninformed: counting backwards in a for loop is faster because comparing an unsigned integer against 0 is generally faster than comparing it against any other value.
No it's not. It generally makes no difference at all.
If you disagree, I dare you to write a benchmark that demonstrates a difference between forward and backward iteration on a modern CPU.
Optimizers eat stuff like this up. It'll restructure your loop however it wants.