匿名数组和数组引用的值得访问，要用@$ 取消引用

代码:

  5 my $aref= [ 1,"foo",undef,13 ];
  6 print @$aref[0]." ";
  7 print @$aref[1]." ";
  8 print @$aref[3]." ";

输出：

1
foo
13