>>23
This isn't what he's suggesting, that is what I am suggesting.
>>24 Can i use this in C89/99?
You can use the map macro, but you won't really gain any thing over just a for loop. You obviously can't use the nested function thing, that's GCC specific.
How does gcc handle scope names if i named another variable _i when using the that?
Just like it would any other scope, it works fine.
>>26
It's O(n) slower than not doing anything at all, and this is noticeable when you don't have to do it.
>>45
It's about O(n/c + k) where k is at most 1/500 the time it takes a neuron to fire and c in the thousands. You won't—can't—notice it unless n is astronomical.
What's slow is managing that memory. Which is waaaaaaaay more than O(n) if it contains pointers or lives for any appreciable amount of time.