Checkbox UPDATE

[Cynaith]

Greetings everyone!

Im having some problems with my script(Warning: Invalid argument supplied for foreach()). Im trying to update posts thats been checked, heres what i got together sofar.

Hope you can help me out here, been searching the internet for hours.

if (isset($_POST["del"])) {
if($HTTP_GET_VARS["event"]=delete)
{
	if($_GET['mail']==inbox)
			{
			$s_del = del_sender;
			}
		else
			{
			$s_del = del_modtager;
			}

foreach($_POST["del_selected"] as $id)
	{
   mysql_query("UPDATE eo_mail SET $s_del = '1' WHERE id='$id'");
	}
}
}
?>

<form name="update" method="post"><input type='submit' name='del' value='Delete Selected'>

<?php
while ($inbox = mysql_fetch_assoc($get_inbox))
			{
			$bgcolor1 = $bgcolor;
			if($bgcolor1==2)
			   {
				$bgcolor1=0;
				}
         switch ($bgcolor1) {

						case "0":
						   $bgcol = EEEEEE;
						   break;

                 case "1":
						   $bgcol = FAF8FB;
						   break;

                 default:
                    $bgcol = EEEEEE;
						   break;
						}

		$bgcolor = $bgcolor1 + 1;
		$inbox_sql = $inbox['sender'];
		$get_users = mysql_query("SELECT * FROM eo_users WHERE id=$inbox_sql") or die(mysql_error());
		$users = mysql_fetch_assoc($get_users);
		If ($inbox['read']==0)
			{
				echo "<tr><td><input type='checkbox' name='del_selected[]' value='".$inbox['id']."'></td><td style=background-color:#".$bgcol."><b>&nbsp;".$users['nickname']."</b></td><td style=background-color:#".$bgcol."><b>&nbsp;".$inbox['message']."</b></td><td style=background-color:#".$bgcol."><b>&nbsp;".date("d/m/Y - H:i",$inbox['dato'])."</b></td></tr>";
			}
		else
			{
				echo "<tr><td><input type='checkbox' name='del_selected[]' value='".$inbox['id']."'></td><td style=background-color:#".$bgcol.">&nbsp;".$users['nickname']."</td><td style=background-color:#".$bgcol.">&nbsp;".$inbox['message']."</td><td style=background-color:#".$bgcol.">&nbsp;".date("d/m/Y - H:i",$inbox['dato'])."</td></tr>";
			}
		}
?>

[nemonoman]

The error will be thrown if non of checkboxes has been checked.

Fix is to check before the foreach:

if($_POST["del_selected"]){
    foreach($_POST["del_selected"] as $id) {
        //etc.
    }
}

}
{

[liquorvicar]

you should probably check that $POST["del_selected"] is actually an array:

if (is_array($_POST["del_selected"]) {
   foreach($_POST["del_selected"] as $id) {
        //etc.
    }
}

just in case someone spoofs your form and puts a normal variable into $POST["del_selected"]. FOREACH will throw up an error if $POST["del_selected"] is not an array (but it won't through an error if it's an empty array).

andy