int num = 999;
int count = 0;
do
{
count++;
num = num/10;
}
while (num>0);
System.ou.println("它是个"+ count + "位的数！");
其中“System.ou.println”应为“System.out.println”，out少了一个t
输出包含：它是个3位的数
while (num>1);