Here are some ways that you can add more data to an array in PHP

1. Use array_push()

array_push() allows you to add new items to the end of the array

Examples below:

Add  an item

$superCars = ["McLaren", "Ferrari", "Lamborghini", "Audi R8"];
array_push($superCars, "Aston Martin");
var_dump($superCars);

Add multiple items

$superCars = ["McLaren", "Ferrari", "Lamborghini", "Audi R8"];
array_push($superCars, "Aston Martin", "Bugatti");
var_dump($superCars);

2. Use array_shift()

array_shift() allows you to add new items at the start of the array.

Example below:

Add an item

$superCars = ["McLaren", "Ferrari", "Lamborghini", "Audi R8"];
array_unshift($superCars, "Aston Martin");
var_dump($superCars);

Add multiple items

$superCars = ["McLaren", "Ferrari", "Lamborghini", "Audi R8"];
array_unshift($superCars, "Aston Martin", "Bugatti");
var_dump($superCars);

3. Add item directly

Using $superCars = [] will add items directly in the array. It is suggested that if you are just adding a few items without much complications this technique will reduce overhead, hence increase performance. 

Add an item

$superCars = ["McLaren", "Ferrari", "Lamborghini", "Audi R8"];
$superCars[] = "Aston Martin";
var_dump($superCars);

Add multiple items

$superCars = ["McLaren", "Ferrari", "Lamborghini", "Audi R8"];
$superCars[] = "Aston Martin";
$superCars[] = "Bugatti";
var_dump($superCars);