PHP trim() not doing what it's supposed to do

Okay, I have a parsed string (a line-fragment from a text), that for some reason have a lot of whitespace - one should think trim() would fix that, but for some reason, it doesn't work.

Here's the relevant part of the code:

foreach($getfile as $line) {
  if (strstr($line, 'h4')) {
  $get_link_id = str_replace('"','',strstr(strstr($line,'"'),'">',true));
  $digit = explode('. ',$line)[0];
  var_dump($digit); //this outputs that the $digit-variable is 19 characters, instead of 1 or 2
  // echo sprintf("%02d", trim($digit)); //this doesn't work, since the string is way too long, and trim() doesn't work - I've tried running trim() outside the sprintf as well
  echo '<li><a href="#'.$get_link_id.'">'.strip_tags($line).'</a></li>';
  }
}

Code (markup):

I would think that trim() should fix this, but it doesn't, and I'm a bit confused... anyone have any idea what I can do?

 

Yeah... I can probably hack together something that will get rid of the problem, but I would much prefer to fix the underlying issue

 

And... I figured it out. It was due to not stripping tags before trying to do the padding.
Ended up changing it to this:

  if (strstr($line, 'h4')) {
  $get_link_id = str_replace('"','',strstr(strstr($line,'"'),'">',true));
  $digit = explode('. ',strip_tags($line));
  $digit[0] = str_replace(" ", "  ", str_pad($digit[0], 2, " ", STR_PAD_LEFT));
  echo '<li><a href="#'.$get_link_id.'">'.$digit[0].'. '.$digit[1].'</a></li>';
  }

PHP: