Judging prime

 public static void main(String args[]){
 3         //1 Neither prime nor sum , Use i from 2 Start .
 4         for(int i=2;i<=1000;i++){
 5             boolean flag = true;
 6             for(int j = 2;j < i;j++){
 7                 if(i % j==0){
 8                     flag = false;
 9                     break;// here we are 1000 The prime number in , Just jump out of the loop , And output the result .
10                 }
11             }
12             if(flag){
13                 System.out.print(" "+i);
14             }
15         }
16     }

C++

#include <stdio.h>
int main(){
    int a=0;  //  The number of primes 
    int num=0;  //  Integer entered 
    printf(" Enter an integer ：");
    scanf("%d",&num);
    for(int i=2;i<num;i++){
        if(num%i==0){
            a++;  //  Prime number plus 1
        }
    }
    if(a==0){
        printf("%d Prime number .\n", num);
    }else{
        printf("%d Not primes .\n", num);
    }
    return 0;
}