Ja, die Variablen-Referenz bleibt auch bei reference nach der foreach bestehen, siehe entsprechende Warnung im PHP Manual: http://php.net/manual/en/control-structures.foreach.php

Also einfach ein unset() zwischen die zwei foreach schieben und gut.

Die Merkwürdigkeit scheint aber auch schon anderen passiert zu sein…

the problem was actually this:

$array = array('a' => array(array(243,453,435,232)));
 
foreach ($array['a'] as &$value) {
         $value[3] = 'aa';
}
var_dump($array);

foreach ($array as $value) {
    var_dump($value);
      foreach ($value as $e) {
          var_dump($e);
           echo implode(',', $e);
     }
}

the problem here is that the second $value is due to the “reference” in the first loop somehow “occupied” with the reference and not newly set, as i thought

so this works:

$array = array('a' => array(array(243,453,435,232)));
 
foreach ($array['a'] as &$value) {
         $value[3] = 'aa';
}
var_dump($array);

foreach ($array as $v) {
    var_dump($v);
      foreach ($v as $e) {
          var_dump($e);
           echo implode(',', $e);
     }
}

all this trouble because of my lazyness to write some chars more
the longer way works of course, as you proposed:

foreach ($array['a'] as $k => $value) {
         $array['a'][$k][3] = $newvalue;
}

Lunchbreak!