初始化后如何访问多维数组中的元素

Question

I have an array

$array = [ [1,2], [3,4] ];

I initialize :

 $array[0][1] = array();
 $array[0][0] = array();

 print_r($array[0][1] =  [ 2 => $array[0][0] ]);

the output is:

Array
(
    [2] => Array
        (
        )

)

But when I try, print_r($array[0][1] = [$array[0][0] => $array[0][0] ]); It will not output as the previous one..what happened?

Answer 1

In php, an assignation return the assigned value.

First

$data[0][1] = [ 2 => $data[0][0] ])

will return

array (
    2 => array ()
)

** Second **

$data[0][1] = [ $array[0][0] => $data[0][0] ]

will return

array (
    array () => array ()
)

In PHP, you can only use ints and strings as a key. This isn't compliant and is an error.