Multiple variables

programming
1

I have a order form setup in .net, but the way the coupon code was setup uses php.

When you hit the submit button it runs a function that calls out a php file, in the php file is the following.

<?php
	$coupon_code= "save10";
	echo $coupon_code;
?>

save10 is the only thing that can be accepted for the discount to work, how can I make multiple coupon codes work at the same time?

Thanks in advance.