PHP如何解释这段代码？

Question

I wanna know how php interprets this code. Is it something of syntax error or matching priorty? I appreciate any help.
Code:

// php 5.3
class Man {
    var $arr = array('name'=>'me');
}

$key = 'name';
$man = new Man();
echo $man->arr['name']; // output me
echo $man->$key['name']; // output nothing along with warning and notice

// output:
PHP Warning:  Illegal string offset 'name' in php shell code on line 1
PHP Notice:  Undefined property: Man::$n in php shell code on line 1

Answer 1

Well, do you mean $key['name'] or $man->$key and ['name'] thereof? It's ambiguous syntax and PHP is interpreting it the former way, trying to get index 'name' of string 'name', resulting in a warning being output and the interpretation being 'name'[0], i.e. 'n'.

Disambiguate the syntax:

$man->{$key}['name']