Fastest way to loop through a 2d array?

Question

I just stumbled upon this blog post. The author shows two code samples that loop through a rectangle and compute something (my guess is the computing code is just a placehol

Answer 1

Cache is indeed the reason, but if you want to know the meat of the argument, you could take a look at the "What Every Programmer Should Know About Memory" by U. Drepper:

http://people.redhat.com/drepper/cpumemory.pdf