<?php  
  
    $agent = strtolower($_SERVER['HTTP_USER_AGENT']);   
    $iphone = (strpos($agent, 'iphone')) ? true : false;   
    $ipad = (strpos($agent, 'ipad')) ? true : false;   
    $android = (strpos($agent, 'android')) ? true : false;   
    if($iphone || $ipad)  
    {  
        echo  <<<END  
        <script>alert('iphone or ipad')</script>  
END;  
    }   
    if($android){  
        echo "<script>alert('android')</script>";  
    }  
?>