求100以内的素数以及个数

注意：

1不是素数

2求素数可以考虑开平方的方法

方法一：

public class prime {

public static void main(String[] args) {

int len = 100;

int count = 0;

int j;

System.out.print(len+"以内的素数为：");

for (int i = 2; i < len; i++) {

int k = (int) Math.sqrt(i);

for (j = 2; j <= k; j++) {

if (i%j == 0) {

break;

}

}

if (j>k) {

count++;

System.out.print(i+" ");

}

}

System.out.println();

System.out.println("素数的个数："+count);

}

}

方法二：

public class prime {

public static void main(String[] args) {

int len = 100;

int count = 1;

System.out.print(len+"以内的素数为："+2+" ");

for (int i = 3; i < len; i++) {

boolean is = true;

int k = (int) Math.sqrt(i);

for (int j = 2; j <= k; j++) {

if (i%j == 0) {

is = false;

break;

}

}

if (is == true) {

count++;

System.out.print(i+" ");

}

}

System.out.println();

System.out.println("素数的个数："+count);

}

}