public class HelloWorld{
public static void main(String[] args){
int num = 999;
int count = 1;
if(num != 0 && num < 1000000000){
for(;num >= 10;count++){
num /= 10 ;
}
System.out.println("它是个"+count+"位的数！");
}else{
System.out.println("输入错误！");
}
