Problems with adding prime numbers in C++
<p>My code works for numbers up to 300 or 20. But it doesn't work for 2000000. I tried using long instead, but it still didn't work.</p>

<pre><code>#include &lt;iostream&gt;
bool prime(int i) {
    bool result = true;
    int isitprime = i;

    for (int j = 2; j &lt; isitprime; j++) { ///prime number tester
        if (isitprime % j == 0) {
            result = false;
            break;
        }
    }

    return result;
}

int main(void) {
    using namespace std;
    long sum = 0;

    for (long i = 2; i &lt;= 2000000; i++) {
        if (prime(i)) {
            sum += i;
        }
    }

    cout &lt;&lt; sum &lt;&lt; endl;
    system("pause");
    return 0;
}
</code></pre>
