java语言的科学与艺术-编程练习11.X

//使用Eratoshene滤网来生成2~1000之间的素数。
import acm.program.*;
public class Eratosthene extends ConsoleProgram {
    public void run(){
        prime = new int[999];
        for(int i = 0; i < 999; i++) {
            prime[i] = i + 2;
        }
        int j = 0;
        int num =0;
        while(true){
            int sign = prime[j];
            for(int i = j + 1; i < 999; i++) {
                if(prime[i] % sign == 0) prime[i] = 0;
            }
            while(true){
                j++;
                if(prime[j] != 0 || j > 997) break;
            }
            if(prime[j] == 0) break;
        }
        //输出素数
        for(int i = 0; i < 999; i++) {
            if(prime[i] != 0) {
                print(prime[i] + " , ");
                num++;
            }
        }
        println("the number of the primes " + num);
    }
    // private instance variables
    private int[] prime;
}