Yeah, I printf() them. Without printing it's 1.8 secs. I have looked into wikipedia on Trial division - Wikipedia, the free encyclopedia, is that the algorithm you use? That is just the "brute force" one right? Then what is perfect to it?

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- 05-02-2009Ideswa
Yeah, I printf() them. Without printing it's 1.8 secs. I have looked into wikipedia on Trial division - Wikipedia, the free encyclopedia, is that the algorithm you use? That is just the "brute force" one right? Then what is perfect to it?

- 05-02-2009laserlightQuote:

Originally Posted by**Ideswa**

The sieve of Eratosthenes is likely to be much faster and yet feasible in this case of just finding the primes less than one million. - 05-02-2009Ideswa
The sieve is memory-heavy though?

So you store primes in an array or something and when you check integer 'n' for primality you check if 'n mod x' != 0 where x are only primes you calculated before?

Edit: I now store validated primes in an array and only use the modulus with the primes in that array. Time without printf() now is 0.7 secs for integers up to 1 million. - 05-02-2009laserlightQuote:

Originally Posted by**Ideswa**

Quote:

Originally Posted by**Ideswa**

- 05-02-2009vampirekid.13
u guys are a lot more advanced than me however, i just made a quick program because it was a project for my c++ tutorial, i appreciate the great advice and as i get further and learn more ill make it better, but as of right now i dont really know how to "break" out of a loop, i know how to skip the prime numbers tho so i guess i can add that in. but yea, you guys prolly did this for years now, im on my first week.