Thread: Prime odd numbers

What would an easy way to detect odd prime numbers? Thanks!

>What would an easy way to detect odd prime numbers?
http://www.gdargaud.net/Humor/OddPrime.html

But seriously, this may help us both (you since it has code, and me since I don't have to post any):
http://www.newdream.net/~sage/old/numbers/primeodd.htm

-Prelude

can anyone post any simple code, or explain the one Prelde gave me? Thanks!

Here's some pseudocode to check primality:

Code:

let the number to be checked be referred to as x
for each odd number(n) greater than 1 and less than the square root of x
	if x is divisible by n then the number is not prime
repeat
if x wasn't divisble by any values of n, it's prime

I'm new w/c, how would i d this?

Originally posted by Lurker
Cant think of anything that works...

This would be your first line:
#include <stdio.h>

Now come on, show a bit of effort. Post again when you have some code.

Ok, heres what i have so far, only displays odd numbers besides 1 right now:

Code:

#include <stdio.h>

int main(void) {
	register int i, n;
	for(i=0; i < 2001; i++) {
		if((i % 2 == 0) || (i == 2) || (i == 1)) continue;
		printf("%d   ", i);
	}
	getchar();
	return 0;
}

>>only displays odd numbers besides 1 right now
How many even prime numbers do you know of?

Use XSquared's pseudo code to help build your C code.

>>I se XSquared pseudo code
It's been a long day

>>Use Prelude's pseudo code to help build your C code

Don't you mean my pseudocode?

Originally posted by Lurker
What would an easy way to detect odd prime numbers? Thanks!

All prime numbers are odd. If it's an even number, it's not prime.

Quzah.

>>Don't you mean my pseudocode?
That was my fault, my brain had a GPF, and I put the wrong name by mistake. Like I said, long day...