Basically the question is if
$color[standard] is better than
$color['standard'] ? Basically the first one is working as well, AS LONG AS there is no constant called “standard” – which is usually not the case.
Still this is bad coding style and quotes should always be used.
$color = array( 'success' => '#00ff00', 'warning' => '#ffff00', 'error' => '#ff0000'); $standard = 'warning'; // working if no constant "standard" but BAD style echo $color[standard]; // working and GOOD coding style echo $color['standard'];