[PHP] Get array as string --Help

[Shelley <myphplist@xxxxxxxxx>]

Hi all,

If I have an array like this:
$arr = array (
                'c' => 'd',
                'e' => 'f');

How can I convert this array into a string? I want to write an array into a
file.

Thanks in advance.

-- 
Regards,
Shelley