public class HelloWorld{
public static void main(String[] args){
int num = 999;
int count = 0;
for(int i=1;i<=1000000000;i=i*10){
while(num/i!=0)
count++;
if(num/i==0)
break;
}
System.out.println("它是个"+count+"位的数");
}
}
int 范围数据溢出
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！");
}