isset和$ _GET混乱

Question

I've created a private messaging system but I have an annoying problem with $_GET.

First of all here's the full code for the "sendmail.php" page which is used for the form to send the mail

<?php
include("header.php");
include("connect.php");

$mailid = $_GET['username'];
$replyname = $_GET['user'];

?>

<form action="send.php" method="post" name="sendpm">
<table>
<tr>
  <td>
     <font color='orange'>To</font>
  </td>
  <?php IF ($mailid != ''){ ?>
  <td>
     <input type="text" name="touser" id="touser" value="<?php echo $mailid;?>"/>
  </td>
  <?php }elseif($replyname != ''){ ?>
  <td>
     <input type="text" name="touser" id="touser" value="<?php echo $replyname;?>"/>
  </td>
  <?php }else{ ?>
  <td>
     <input type="text" name="touser" id="touser" value="<?php echo $replyname;?>"/>
  </td>
  <?php } ?>
</tr>
<tr>
  <td>
     <font color='orange'>Subject</font>
  </td>
  <td>
     <input type="text" name="subject" id="subject" />
  </td>
</tr>   
<tr>
  <td>
     <font color='orange'>Message</font>
  </td>
  <td>
     <textarea name="message" cols="60" rows="10" id="message"></textarea>
  </td>
</tr>
<tr>
  <td colspan="2">
     <input type="submit" value="Send PM" />
  </td>
</tr>
</table>
</form>

<?php
include("footer.php");
?>

Okay so as you can see here

$mailid = $_GET['username'];
$replyname = $_GET['user'];

I can get two different results depending on where it comes from. The "mailid" is if you've been directed from a profile. The "replyname" is if you've clicked "reply" to a message you've received.

Now, if I try to send a mail from scratch, I will be told that "username" and "user" are undefined (as I haven't come from the links that include them). If I come from one link then the other will be undefined and vice versa.

I can 'solve' this by adding isset but for some reason, that keeps displaying a "1" instead of the username that should be shown (and IS shown if I follow a link without isset).

This is very annoying and I've been trying to solve it for ages!

I just realised isset deals in true or false. So the "1" means it's true, so I've changed it to

IF(isset($_GET['username'])){
$mailid = $_GET['username'];
}

IF(isset($_GET['user'])){
$replyname = $_GET['user'];
}

I thought this would be fine but still shows 1?

Answer 1

Well i would like to see how you are using isset. If you are trying something like this

$mailid = isset($_GET['username']);
$replyname = isset($_GET['user']);

Then it will return boolean.

Try this.

<?php
include("header.php");
include("connect.php");
?>
<form action="send.php" method="post" name="sendpm">
<table>
<tr>
  <td>
     <font color='orange'>To</font>
  </td>
  <td>
     <input type="text" name="touser" id="touser" value="<?php echo isset($_GET['username'])?$_GET['username']:$_GET['user']; ?>"/>
  </td>
</tr>
<tr>
  <td>
     <font color='orange'>Subject</font>
  </td>
  <td>
     <input type="text" name="subject" id="subject" />
  </td>
</tr>   
<tr>
  <td>
     <font color='orange'>Message</font>
  </td>
  <td>
     <textarea name="message" cols="60" rows="10" id="message"></textarea>
  </td>
</tr>
<tr>
  <td colspan="2">
     <input type="submit" value="Send PM" />
  </td>
</tr>
</table>
</form>

and dont forgot to filter your input.