more efficient way to check 2 array foreach values

Question

Is there a more efficient way to foreach check an array for similar values against multiple arrays? Here's my code:

foreach ($city as $option) {
    if (in_array($option, $optionarray1)) {
        $tables[] = 'newvalue1';
    } else if (in_array($option, $optionarray2)) {
        $tables[] = 'newvalue2';
    } else if (in_array($option, $optionarray3)) {
        $tables[] = 'newvalue3';
    }
 }

given you're adding different values for each comparison, no... not really. — Marc B
– Marc B, Commented Sep 14, 2016 at 21:35

Barmar · Accepted Answer · 2016-09-14 21:35:53Z

1

Use array_flip() to turn each $optionarrayX into an associative array, so you don't have to do linear searches each time.

$optionhash1 = array_flip($optionarray1);
$optionhash2 = array_flip($optionarray2);
$optionhash3 = array_flip($optionarray3);

Then you can put these all in an array, so you can use a nested loop instead of repeating code.

$optionhashes = array(1=>$optionhash1, 2=>$optionhash2, 3=>$optionhash3);

foreach ($city as $option) {
    foreach ($optionhashes as $i => $hash) {
        if (array_key_exists($option, $hash)) {
            $tables[]= 'newvalue' . $i;
            break;
        }
    }
}

answered Sep 14, 2016 at 21:35

Barmar

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