PHP Browser Detecting

<?php
if(strpos($_SERVER[‘HTTP_USER_AGENT’], ‘MSIE’) !== FALSE)
echo ‘Internet explorer’;
elseif(strpos($_SERVER[‘HTTP_USER_AGENT’], ‘Firefox’) !== FALSE)
echo ‘Mozilla Firefox’;
elseif(strpos($_SERVER[‘HTTP_USER_AGENT’], ‘Chrome’) !== FALSE)
echo ‘Google Chrome’;
else
echo ‘Something else’;
?>