PHP: Double square brackets after a variable?

Question

echo $a['b']['b2'];

What does the value in the brackets refer to? Thanks.

Answer 1

This is an array.

what you are seeing is

    <?php
    $a = array(
        'b' => array(
          'b2' => 'x'
        )
    );

So in this case, $a['b']['b2'] will have a value of 'x'. This is just my example though, there could be more arrays in the tree. Refer to the PHP Manual