prime.cpp

#include<iostream>

using namespace std;
int main()
{
    int N = 100;
    int is_prime[N+1];

    /* initialize */
    for (int i = 1; i <= N; i++)
        is_prime[i]=1;

    /* 1 is not a prime */
    is_prime[1]=0;


    for (int i = 2; i*i <= N; i++)
        if (is_prime[i])
            for (int j = i; j*i <= N; j++)
                is_prime[j*i]=false;

    /* print every prime <= N */
    for (int i = 1; i <= N; i++)
        if (is_prime[i])
            cout << i << endl;
}