PHP运算符问题

&&优先级比=高,所以会$a = (100 && $b = 200),在http://php.com/manual/en/language.operators.precedence.php中有一句
Although = has a lower precedence than most other operators, PHP will still allow expressions similar to the following: if (!$a = foo()), in which case the return value of foo() is put into $a.,虽然&&优先级高于=,但是200还是会被赋值给$b,由于100 && $b = 200均为真返回true,所以$a=true

实际上的优先级是这样的：

php
if($a = (100 && $b = 200)){
    var_dump($a, $b);
}