$arr = array();
$arr["name"] = "marjel101";
$arr["course"] = "PHP";

Test if a certain key is set in the array:

array_key_exists("course", $arr)

Test if a certain key is set in the array:

isset($arr["course"] ? "course is set" : "course is not set";

This is the same as 'isset', but a new method, PHP7:

$arr["course"] ?? "course is not set";

$arr["address"] ?? "address is not set";

"; $address = $arr["address"] ?? "address is not set"; echo "address = $address"; ?>

How many elements in an array:

"count: " . count($arr);

Returns a boolean value if the argument is an array (1) or not (0).

is_array($arr);

Please leave a comment if you see an error or if you like to add something I can learn from.

A few array functions - part I - PHP