get first and last element in array

Question

hey there i have this array:

array(1) {
  [\"dump\"]=>
  string(38) \"[\"24.0\",24.1,24.2,24.3,24.4,24.5,24.6]\"
}

my question:

Answer 1

As of PHP 7.3, array_key_first and array_key_last is available

$first = $array[array_key_first($array)];    
$last = $array[array_key_last($array)];