if(num>=0 && num<=999999999){
while(num!=0)
{
count++;
num=num/10;
}
System.out.println("它是个"+count+"位的数!");
}
else { System.out.println("输入有误");}
public class HelloWorld{
public static void main(String[] args){
int num=999; //记得初始化num和count这两个变量
int count=0;
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！");
}
}
}