PHP: Adding prefix strings to array values

Question

What is the best way to add a specific value or values to an array? Kinda hard to explain, but this should help:

Answer 1

Below code will add "prefix_" as a prefix to each element value:

$myarray = array("test", "test2", "test3");    
$prefixed_array = preg_filter('/^/', 'prefix_', $myarray);

Output will be:

Array ( [0] => prefix_test [1] => prefix_test2 [2] => prefix_test3 )