add array to array php

$myArr = [1, 2, 3, 4];

array_push($myArr, 5, 8);
print_r($myArr); // [1, 2, 3, 4, 5, 8]

$myArr[] = -1;
print_r($myArr); // [1, 2, 3, 4, 5, 8, -1]<?php
$array1 = array("color" => "red", 2, 4);
$array2 = array("a", "b", "color" => "green", "shape" => "trapezoid", 4);
$result = array_merge($array1, $array2);
/*
Array
(
    [color] => green
    [0] => 2
    [1] => 4
    [2] => a
    [3] => b
    [shape] => trapezoid
    [4] => 4
)
*/
?>$myArray = array("name" => "my name");
echo json_encode($myArray);array_push($cart, 13);
$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>";