循环切换或切换循环

Question

I was wondering which code is effective. Notice, that $type = 1 is same during the whole loop.

if(!$handle = opendir('.')) {
    return false;
}

$result = array();
while(false !== ($entry = readdir($handle))) {
    if(!$resDir = self::getUrlByType($type, $entry)){
        continue;   
    }

    switch($type) {
        case 1:
            /* do something */
            break;

        case 2:
            /* do something different */
            break;
    }
}
closedir($handle);

I think, that these both codes should be proceesed with same duration, because it is only one condition there.

if(!$handle = opendir('.')) {
    return false;
}

switch($type) {
    case 1:
        $result = array();
        while(false !== ($entry = readdir($handle))) {
            if(!$resDir = self::getUrlByType($type, $entry)){
                continue;   
            }

            /* do something */
        }
        break;

    case 2:
        $result = array();
        while(false !== ($entry = readdir($handle))) {
            if(!$resDir = self::getUrlByType($type, $entry)){
                continue;   
            }

            /* do something different */
        }
        break;
}


closedir($handle);

I made negative microtime footprint at the begining of each script $time = -microtime(true); and the difference between current microtime $time += microtime(true); at the end of script. After i displayed the results echo "Time: ", sprintf('%f', $time), " "; i saw these values:

Time of first script was average between 0.0084 and 0.0203.

The secon results were much different, average between 0.0062 and 0.0072.

My question is, what is the case of this behaviour? Why didnt PHP compiler cashed that?

This ist the PHP output:

Type: 1
Type: 1
Type: 1
Type: 1
Type: 1
Type: 1
Type: 1
Type: 1
Time: 0.000103
Type: 1
Type: 1
Type: 1
Type: 1
Type: 1
Type: 1
Type: 1
Type: 1
Time: 0.000065

Answer 1

A loop inside a switch would be preferred, in my opinion. There can be a case where it may make more sense one way or the other so this depends on the scenario.

But on a logistical stand point, having a loop inside of a switch means you only have to check for one condition and loop through a lot of "known" process. While if you loop a switch it constantly checks a state then does one process of known code just to repeat itself with a bit more overheard.