php detect _SERVER['HTTP_USER_AGENT'] is IE 8, 9, 10, 11

<?php
echo $_SERVER['HTTP_USER_AGENT'];exit;
preg_match('/MSIE (.*?);/', $_SERVER['HTTP_USER_AGENT'], $matches);
if(count($matches)<2){
  preg_match('/Trident\/\d{1,2}.\d{1,2}; rv:([0-9]*)/', $_SERVER['HTTP_USER_AGENT'], $matches);
}

if (count($matches)>1){
  //Then we're using IE
  $version = $matches[1];

  switch(true){
    case ($version<=8):
      //IE 8 or under!
 echo '8';
      break;

    case ($version==9 || $version==10):
      //IE9 & IE10!
 echo '9-10';
      break;

    case ($version==11):
      //Version 11!
 echo '11';
      break;

    default:
echo $version;
      //You get the idea
  }
}