答案沒問(wèn)題C的左右都為true,又因?yàn)?amp;&是與運(yùn)算，與運(yùn)算就是如果兩邊都為true，那結(jié)果就是true,由題可知C為正確選項(xiàng)。

public?class?HelloWorld{
public?static?void?main(String[]?args){
int?num?=?999;
int?count?=?0;
if(num>=0&&num<=999999999){
????while(num!=0)
????{
????????count++;
????????num=num/10;
????}
????System.out.println("它是個(gè)"+count+"位的數(shù)！");
}else{
????System.out.println("輸入有誤!?");
}
}
}