[php] How to add elements to an empty array in PHP?

If I define an array in PHP such as (I don't define its size):

$cart = array();

Do I simply add elements to it using the following?

$cart[] = 13;
$cart[] = "foo";
$cart[] = obj;

Don't arrays in PHP have an add method, for example, cart.add(13)?

REMEMBER, this method overwrites first array, so use only when you are sure!

$arr1 = $arr1 + $arr2;

(see source)

Based on my experience, solution which is fine(the best) when keys are not important:

$cart = [];
$cart[] = 13;
$cart[] = "foo";
$cart[] = obj;

$cart = array();
$cart[] = 11;
$cart[] = 15;

// etc

//Above is correct. but below one is for further understanding

$cart = array();
for($i = 0; $i <= 5; $i++){
          $cart[] = $i;  

//if you write $cart = [$i]; you will only take last $i value as first element in array.

}
echo "<pre>";
print_r($cart);
echo "</pre>";

$products_arr["passenger_details"]=array();
array_push($products_arr["passenger_details"],array("Name"=>"Isuru Eshan","E-Mail"=>"[email protected]"));
echo "<pre>";
echo json_encode($products_arr,JSON_PRETTY_PRINT);
echo "</pre>";

//OR

$countries = array();
$countries["DK"] = array("code"=>"DK","name"=>"Denmark","d_code"=>"+45");
$countries["DJ"] = array("code"=>"DJ","name"=>"Djibouti","d_code"=>"+253");
$countries["DM"] = array("code"=>"DM","name"=>"Dominica","d_code"=>"+1");
foreach ($countries as $country){
echo "<pre>";
echo print_r($country);
echo "</pre>";
}

You can use array_push. It adds the elements to the end of the array, like in a stack.

You could have also done it like this:

$cart = array(13, "foo", $obj);

When one wants elements to be added with zero-based element indexing, I guess this will work as well:

// adding elements to an array with zero-based index
$matrix= array();
$matrix[count($matrix)]= 'element 1';
$matrix[count($matrix)]= 'element 2';
...
$matrix[count($matrix)]= 'element N';

It's better to not use array_push and just use what you suggested. The functions just add overhead.

//We don't need to define the array, but in many cases it's the best solution.
$cart = array();

//Automatic new integer key higher than the highest 
//existing integer key in the array, starts at 0.
$cart[] = 13;
$cart[] = 'text';

//Numeric key
$cart[4] = $object;

//Text key (assoc)
$cart['key'] = 'test';

Both array_push and the method you described will work.

$customArray = array();
$customArray[] = 20;
$customArray[] = 21;

Above is correct, but below one is for further understanding

$customArray = array();
for($i=0;$i<=12;$i++){
    $cart[] = $i;  
}
echo "<pre>";
print_r($customArray);
echo "</pre>";