第一次代码:

 int sum=999;

int count=1;

while(sum>=0&&sum<1000) {

while(sum/10!=0) {

count++;

sum=sum/10;

}

System.out.println("999是个"+count+"位数");

}

第二段代码:

int sum=999;

int count=1;

while(sum/10>0&&sum/100<10) {

while(sum/10!=0) {

count++;

sum=sum/10;

}

System.out.println("999是个"+count+"位数");

}