how to add array elements in php code example

Example 1: php append to array

$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]

Example 2: php append element to array

array_push($cart, 13);