若两个素数之差为2，则称其为孪生素数

 

package 孪生素数;public class 孪生素数 {    public static void main(String[] args)    {        int i,j;        int flag, n = 0;        int a[] = new int[100];                for(i = 2; i <= 100; i++)        {            flag = 1;                        for(j = 2; j < i; j++)            {                if(i%j == 0)                {                    flag = 0;                    break;                }            }                        if(flag == 1)            {                a[n] = i;                n++;            }                    }                System.out.println("100以内的孪生素数如下：");                for(i = 0; i < n-1; i++)        {            if(a[i+1]-a[i] == 2)            {                System.out.print(a[i]+" ");                System.out.print(a[i+1]+" ");                System.out.println("\n");            }        }    }}