这样写不对吗？

public class HelloWorld{
public static void main(String[] args){
int num = 999;
int count = 0;
if ((num >= 0)&&(num <= 1000000000)){
    for(;num < 10;count++){
    for(;num < 10;){
        num = num/10;
    }
    }
}
System.out.println("它是个"+count+"位的数！");
}
}