public class HelloWorld{
public static void main(String[] args){
int num = 999;
int count = 0;
for(;num>0;num=num/10){
count++;
}
System.out.println("它是个"+count+"位的数!");
已经可以通过了
do{ num = (num - (num % 10)) / 10; count++;}while(num > 0);System.out.println("它是个"+count+"位的数!");
少两个}}