I'm trying to append a string to an array value and it doesn't seem to be working. Can someone tell me what I'm doing wrong? The array values will be URLs with a trailing forward slash.

http://www.mywebsite.com/Details/product-type/New-York-293486/

$values[10] .= '?cid=spontrue';

The code you posted will work to append the string to the end of whatever value $values[10] has. If its not working the problem is elsewhere.