php add item to array

<?php
$a=array("red","green");
array_push($a,"blue","yellow");
print_r($a);
?>

<?php
  $z = ['me','you', 'he'];
  array_push($z, 'she', 'it');
  print_r($z);
?>

<?php

$a=array("red","green");

array_push($a,"blue","yellow");

print_r($a);
?>

<?php

$a=array("red","green");

array_push($a,"blue","yellow");

print_r($a);
?>
 

<?php
$stack = array("orange", "banana");
array_push($stack, "apple", "raspberry");
?>

$cart = array();
$cart[] = 13;
$cart[] = 14;
// etc

//Above is correct. but below one is for further understanding
$cart = array();
for($i=0;$i<=5;$i++){
    $cart[] = $i;  
}
echo "<pre>";
print_r($cart);
echo "</pre>";