Example of prime numbers searching in C++ using list (with ptimizations)

prime-opt.cpp

#include <list>
#include <iostream>
#include "math.h"

using namespace std;

bool isPrime(int n, list<int> &primes) {
	for (list<int>::iterator iter = primes.begin(); iter != primes.end(); ++iter)
		if (*iter > (int) pow(n*1., 0.5) + 1)
			return true;
		else if (n % *iter == 0) 
			return false;
	return true;
}

list<int> primes(int num) {
	list<int> primes;
	for (int i = 2; i < num; i++)
		if (isPrime(i, primes))
			primes.push_back(i);
	return primes;
}

int main() {
	list<int> pr = primes(1000000);
	cout << '[';
	for (list<int>::iterator iter = pr.begin(); iter != pr.end(); ++iter)
		cout << *iter << ',';
	cout << ']' << endl;
	return 0;
}