Select values from an array by array of keys

Question

I have two arrays of the same length containing some values.

$a = array("a","b","x","x");
$b = array("f","g","g","h");

Now I want to get the values from $b at the index postions from where $a is x.

 $ids = array_keys($a, 'x');
 $res = ???($b,$ids);
 print_r($res);

So what function will give me an Array containing g and h. Or is there even a more elegent (e.g. not using array_keys()) to do this?

array_intersect_key($b, preg_grep('/^x$/D', $a)) (Using regex is clearly, always, the more elegant solution. *grin*) — salathe, Jan 19 '13 at 12:48

Your Common Sense · Answer 1 · 2013-01-19 12:10:35Z

up vote 1 down vote

$needle = 'x';
$res    = array();
foreach($a as $key => $value) {
    if ($value == $needle) {
        $res[] = $b[$key];
    }
}

answered Jan 19 '13 at 12:10

Your Common Sense
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1 Answer