array_push, count, append

<h1>function</h1>

<?php

header("Content-Type: text/html; charset=UTF-8");

$adata = array('a', 'b', 'c');

array_push($adata,'d');

foreach($adata as $item){

    echo $item."<br />";

}

var_dump(count($adata));

?>

<h1>oop</h1>

<?php

$odata = new ArrayObject(['a', 'b', 'c']);

$odata->append('d');

foreach($odata as $vals){

    echo $vals."<br />";

}

var_dump($odata->count());

?>