[Houshalter]

Would could possibly be the advantage of hard coding divisibility checks against every prime number? There's so many problems with this. The simplest thing would be to just make an array of primes and iterate through it. There's also faster algorithms to check for primality.

[adrianratnapala]

That code is making an array of primes and iterating through it. It's just that the array is stored in instruction memory, and there is no explicit fiddling with indices or pointers.

As for more advanced primality testing methods, I guess it depends on where the the fancier algorithms begin to pay off. It would not surprise me if this simple algorithm was the fastest for any input small enough to be stored in a single machine word.