请问我的代码怎么错了
public class HelloWorld{
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");
}
}
}
