primes/primes.cpp

// C++ version of a Prime Number Finder
// haplo@mindstab.net

#include <iostream>
#include <math.h>
#include <string>
#include <stdlib.h>

using namespace std;

class CPrimes 
{
	public:
		void countPrimes(unsigned int MAX);
};

	
void CPrimes::countPrimes(unsigned int MAX)
{
	for(unsigned int cnt = 3; cnt <= MAX; cnt+=2)
	{
		int test = (int)sqrt((double)cnt);
		char isPrime=1;
		for(int i = 3; i<= test; i+=2)
		{
			if(! (cnt % i))
			{	
				isPrime = 0;
				break;
			}
		}

		if(isPrime)
		{
			cout << cnt << endl;
		}
	}
}

int main(int argc, char **argv)
{
	
	int MAX;
	if(argc <= 1) {
		cout << "Useage: primescpp [Max Num]" << endl;
		return(1);
	} else {
		MAX = atoi(argv[1]);
	}

	if(MAX < 1) {
		cout << "Invalide Max Num" << endl;
		return(1);
	}

	CPrimes *primes = new CPrimes();
	primes->countPrimes(MAX);
	delete primes;

	return(0);
}