仅在应该显示时显示 - 否则隐藏

Question

Can someone tell me how I can get this code to not show the app download button on a device that is not listed below?

I know it can be done but I'm not really sure.

Thanks.

<?php
$ua=$_SERVER['HTTP_USER_AGENT'];
switch(true) {
  case stripos($ua,'android') :
    $device = 'android'; break;
  case stripos($ua,'ipad') :
    $device = 'ipad'; break;
  case stripos($ua,'iphone') :
    $device = 'iphone'; break;
}
?> 
<ul class="pageitem"><li class="button android"><input name="Submit" value="App Downloads" onclick="window.location='apps.php?id=<?php echo $device; ?>' " type="submit" /></li></ul>

Answer 1

Try with default case. If not matches, default case will work.

<?php
$ua=$_SERVER['HTTP_USER_AGENT'];
switch(true) {
  case stripos($ua,'android') :
    $device = 'android'; break;
  case stripos($ua,'ipad') :
    $device = 'ipad'; break;
  case stripos($ua,'iphone') :
    $device = 'iphone'; break;
  default:
    $device = false;
}
?> 

<?php if($device): ?>
<ul class="pageitem"><li class="button android"><input name="Submit" value="App Downloads" onclick="window.location='apps.php?id=<?php echo $device; ?>' " type="submit" /></li></ul>
<?php endif; ?>