Sieve of Eratosthenes algorithm

Question

I am currently reading \"Programming: Principles and Practice Using C++\", in Chapter 4 there is an exercise in which:

I need to mak

Answer 1

Here's my implementation not sure if 100% correct though : http://pastebin.com/M2R2J72d

#include
#include  

using namespace std;
void listPrimes(int x);

int main() {

    listPrimes(5000);
}

void listPrimes(int x) {
    bool *not_prime = new bool[x];
    unsigned j = 0, i = 0;

    for (i = 0; i <= x; i++) {
        if (i < 2) {
            not_prime[i] = true;
        } else if (i % 2 == 0 && i != 2) {
            not_prime[i] = true;
        }
    }

    while (j <= x) {
        for (i = j; i <= x; i++) {
            if (!not_prime[i]) {
                j = i;
                break;
            }
        }
        for (i = (j * 2); i <= x; i += j) {
            not_prime[i] = true;
        }
        j++;
    }

    for ( i = 0; i <= x; i++) {
        if (!not_prime[i])
            cout << i << ' ';
    }

    return;
}