public class HelloWorld{

public static void main(String[] args){

int num = 999;

int count = 0;

int j;

int i=100000000;

if (i>=0&&i<=999999999){

  for(;count>=9;count++){

     j=9-count;

    if(num/i != 0)

        System.out.println("它是个"+j+"位数");

    else

    i=i/10;

  }

}

else

System.out.println("错误");

}

}