Checking a key in an array

Check if a key exists in the array: key_exists()

The key_exists() function is an alias array_key_exists(). You can use key_exists() in order to check if the key exists and you can access it.

For a non-associative array the keys are 0, 1, 2 …

$arr = ["a", "b"];
$exists = key_exists(0, $arr); // true
$exists = key_exists(1, $arr); // true
$exists = key_exists(2, $arr); // false

For an associative array

$arr = ["a" => "first one", "b" => "second one"];
$exists = key_exists("a", $arr); // true
$exists = key_exists("b", $arr); // true
$exists = key_exists("c", $arr); // false