highlight Search Words 

<?php
function highlight($word, $subject) {
    
    $split_subject = explode(" ", $subject);
    $split_word = explode(" ", $word);

    foreach ($split_subject as $k => $v){
           foreach ($split_word as $k2 => $v2){
               if($v2 == $v){
                   
                   $split_subject[$k] = "<span class='highlight'>".$v."</span>";
               
               }
           }
      }
      
      return implode(' ', $split_subject);
}
?>