多重循环，搞不明白为什么对不了、
import java.util.Scanner;
public class duochongxunhuan2 {
public static void main(String[] args){
Scanner in = new Scanner(System.in);
System.out.println("请输入1~999999999之间的数字 ");
int t = in.nextInt();
int a = 0;
int b = 0;
if(a>=1&&a<=999999999){
while(a>=1){
a=a/10;
b++;
}
System.out.println("这是个"+(b-1)+"位数");
}else{
System.out.println("输入有误");
}
}
}
