/**
 * This class performs Erathostenes sieve method,
 * please refer to COSC229 tutorial 5 (4)
 * 
 * @author Sharon Duan
 * @version Oct 2007
 */
public class Sieve
{
    private int n; 
    private int[] a;

    /**
     * Constructor for objects of class Sieve
     */
    public Sieve(int n)
    {
        this.n = n;
        a = new int[n+1];
    }

    public void sieveout()
    {
        int i=2; // start with sieving by 2
        while(i*i<=n){ // when i<=sqrt(n)
            for(int x=i+1; x<=n; x++){ // for each x where i+1<=x<=n
                if(x%i==0) a[x]=1; // set x as a composite if x=0 mod i
            }
            i++; // increase i
        }
        printPrimes();
    }
    
    private void printPrimes()
    {
        System.out.println("n = " + n);
        for(int j=2; j<=n; j++){
            if(a[j]==0) System.out.println(j);
        }
    }
    
    public void setN(int n)
    {
        this.n = n;
        a = new int[n+1];
    }
}