Active Sidebar Conditional Question?

If I am reading this right, all you need is a count of the active sidebars, so:

$col = 0;
if(is_active_sidebar('footer')) {
  $col++;
} 
if(is_active_sidebar('footer-2')) {
  $col++;
} 
if( is_active_sidebar('footer-3')) {
  $col++;
}?>

<div class="<?php echo 'column-'.$col; ?>">

Note: I flipped the “column” class so that it begins with a letter. Numbers are not allowed as the first character. If you wanted to convert that to “one”, “two”, etc you should be able to cook that up yourself without much effort but it doesn’t seem worth the overhead to me when a simple structural change makes it unnecessary.