Why my array variable is empty when I filled it in a loop?

Question

$crawler = new Crawler($xml);

$parkList = []; 

$crawler->filter('wfs|FeatureCollection > gml|featureMember > bm|ST_PARK_P > bm|NOM')->each(function (Crawler $actualPark, $i) {
        $parkList[$i] = [];
        $parkList[$i][] = $actualPark->text();
        //var_dump($parkList); // $parklist variable is filled
});

$crawler->filter('wfs|FeatureCollection > gml|featureMember > bm|ST_PARK_P > bm|geometry > gml|Point > gml|pos')->each(function (Crawler $actualPark, $i) {
        $parkList[$i][] = explode(' ', $actualPark->text())[0];
});
$crawler->filter('wfs|FeatureCollection > gml|featureMember > bm|ST_PARK_P > bm|geometry > gml|Point > gml|pos')->each(function (Crawler $actualPark, $i) {
        $parkList[$i][] = explode(' ', $actualPark->text())[1];
});


return $parkList; //parklist variable is strangely empty

Why my parkList variable is empty outside the .each function whereas I declared it outside the loop and fill its value during the loop... and the loop is successfully executed ?

Share minimum reproducible example. At a glance, it looks it will need the use of `use` and `&` — nice_dev, Apr 25 '21 at 14:46

score 0 · Answer 1 · answered Apr 25 '21 at 14:52

You're adding it to a local variable $parkList, not your global variable. Here is an demo for the different variable behaviour.

$list = [];

$localVariable = function() {
    $list[] = 'one';
};
$globalVariable = function()  {
    $GLOBALS['list'][] = 'two';
};
$defineLocalVariableAsGlobal = function() {
    global $list;
    $list[] = 'three';
};
$useListAsReference = function() use (&$list) {
    $list[] = 'four';
};

$localVariable();
$globalVariable();
$defineLocalVariableAsGlobal();
$useListAsReference();

var_dump($list);

Output:

array(3) {
  [0]=>
  string(3) "two"
  [1]=>
  string(5) "three"
  [2]=>
  string(4) "four"
}

I would suggest providing the variable with use. This work even with nested calls. The other two ways only work for a global variable.

Because it is an array you need to provide it as an reference to be able to modify it. This would not be the case for objects.

Why my array variable is empty when I filled it in a loop?

1 Answers1