The best way to do this is JSON serializing. It is human readable and you’ll get better performance (file is smaller and faster to load/save). The code is very easy. Just two functions
Example code:
$arr1 = array ('a'=>1,'b'=>2,'c'=>3,'d'=>4,'e'=>5);
file_put_contents("array.json",json_encode($arr1));
# array.json => {"a":1,"b":2,"c":3,"d":4,"e":5}
$arr2 = json_decode(file_get_contents('array.json'), true);
$arr1 === $arr2 # => true
You can write your own store_array and restore_array functions easily with this example.
For speed comparison see benchmark originally from Preferred method to store PHP arrays (json_encode vs serialize).