数组未设置时php切换的行为

Question

So, I'm trying to have a better understanding of how switch would act when an array is not set and if I should use isset() and/or default:

Example, of the code I'm currently using:

$parameters['sort'] = NULL;

if(isset($parameters['sort'])) {

    switch($parameters['sort'])
    {
        case 'relevance':
            $parameters['sort'] = 'rating';
        break;
        case 'published':
            $parameters['sort'] = 'updated';
        break;
        case 'views':
            $parameters['sort'] = 'viewCount';
        break;
    }

}

Note: I know the break; doesn't have the right indent (should be as below), but it's how I like using it in switch().

Note2: I'm just reviewing my code to fix bugs and improve it while making better sense of how things should be properly implemented/used

    case 'relevance':
        $parameters['sort'] = 'rating';
        break;

So my question is, should I add the extra default and remove the if() or continue using the if() as it didn't caused any problem? Using both wouldn't make any sense!

    default:
        $parameters['sort'] = '';
    break;

Answer 1

default option will be chosen after checking all prior comparisons. If default will be the most common choice and the code will be heavily executed, I think you should stick to the if clause, and you won't have to trust any auto optimizations to save you processor time.