ARRAYS THAT WILL CONCATTENATE TEXT AND NUMBERS

Question

I have a form in visual studio 2008. one button and two text box1 and 2 and 1 combobox

The user selects a horsename from combo which updates textbox1. 

i have the following array which is in php and will like to convert to fit visual.

$ar = array('A' => 1,

'B' => 2,

'C' => 3,

'D' => 4,

'E' => 5);

when the user selects a horsename "DAB" WHICH updates textbox1. i want the form to work out that "DAB" is "4+1+2=7" and show in textbox3 as 7

please help as i have downloaded vs.php and phalenger3 but i am still stuck as i cannot activate it with my hkey.