change array size using array_pad() in php

<?php

$num=array(1,2,3,4,5,6,7,8,9,10);
echo '<b>array before grow elements :</b>';
foreach($num as $num1)
{
echo ' '.$num1;
}
echo '<br><br>';

$num = array_pad($num, 20,'a') ; //only additionally adding elements have 'a' value

// $num = array_pad($num, 20,'') ; additionally adding elements have empty

echo '<b>array after grow elements :</b>';
foreach($num as $num1)
{
echo ' '.$num1;
}


?>


output :

array before grow elements : 1 2 3 4 5 6 7 8 9 10

array after grow elements : 1 2 3 4 5 6 7 8 9 10 a a a a a a a a a a

 note :

1) just modify  " $num = array_pad($num, 20,'a') ;  " as "  $num = array_pad($num, 20,'') ; "  for empty
2) that means array index raise but with empty values