I'm new to PHP.. I want to know how can you apply a function on a specific value of Array

I've attached the code & SQL file, since this codes uses PHP classes, I'm not able to convert my DATE fields while displaying them from the DB & inserting them to the DB..

I have commented the date Conversion function in the example.php, but I'm not able to Apply it to the Field in the array..
I'm actually stuck at line no 20 in Example.php where is it populating the array from the Database fields.

$tabledit->fields_in_list_view = array('uc_event_id','date_of_event','event_desc');

I just need to apply a function to Item[2] of this array & convert the String to Date format of dd-mm-yyyy

Likewise I need help when Adding/Editing records, the datepicker sets correct format of date (dd-mm-yyyy) but to enter it to MySQL DB I will need to convert it to YYYY-MM-DD

Pls help me with this... I'll be really thankful