get_nth_prime_without_sieve.cpp

unsigned long get_nth_prime_without_sieve(unsigned long n) {
	
	if (n == 0) return 0;
	if (n == 1) return 2;

	unsigned long prime_num = 3;
	unsigned long local_n = 2;	// 2th prime number is 3

	while (local_n != n) {
		
		// check next prime number candidate
		prime_num += 2;	// 3,5,7,9... check only odd numbers

		if (isPrime(prime_num) == true) {
			local_n++;
		}
	}

	return prime_num;
}