这道练习题的这两种实现方式都对吗？

1. public class Pratice{
   public static void main(String[] args){
   int num = 999;
   int count = 0;
   if(num>=0&&num<=999999999){
    for(;num!=0;){
        count++;
        num=num/10;
    }
   System.out.println("它是个" + count + "位的数！");
   }
   else {
       System.out.println("number is invalid");
   }
   }
   }
   

2. public class Practice{
   public static void main(String[] args){
   int num = 999;
   int count = 0;

   if (num >= 0  && num<=999999999){
   while(num != 0){
   count++;
   num/=10;
   }
   System.out.println("它是个"+ count+"位的数！");
   } else{
   System.out.println("输入有误！");
   }

   }

   }