HELP Please PHP Parse error

Getting PHP Parse error: syntax error, unexpected T_ELSE in /home/aussiea1/public_html/classified_ad.php on line 18, below are the first 50 lines of code ur help is greatly apprieciated
<?

session_start();

error_reporting(0);

require 'include/connect.php';

$user_id=$HTTP_SESSION_VARS[userid];

if($_GET)

$badwords = array("union", "select", "join", "concat", "from", "UNION", "SELECT", "JOIN", "CONCAT", "FROM");
$corrected = str_replace($badwords,"getalife",$_GET['item_id']);
$item_id = $corrected;
echo $item_id;

else if($_POST)

$badwords = array("union", "select", "join", "concat", "from", "UNION", "SELECT", "JOIN", "CONCAT", "FROM");
$corrected = str_replace($badwords,"getalife",$_POST['item_id']);
$item_id = $corrected;
echo $item_id;

$badwords = array("union", "select", "join", "concat", "from", "UNION", "SELECT", "JOIN", "CONCAT", "FROM");
$corrected = str_replace($badwords,"getalife",$_GET[mode]);
$mode = $corrected;
echo $mode;

/* if(empty($HTTP_SESSION_VARS[userid]))

{

echo '<meta http-equiv="refresh" content="0;url=signin.php?url=detail.php&item_id='.$item_id.'&mode='.$mode.'">';

echo "<font size=+1 color=#003366>Loading....</font>";

exit();

} */

$bid_sql="select * from placing_item_bid where item_id=".$item_id;

$bid_res=mysql_query($bid_sql);

$row=mysql_fetch_array($bid_res);



$high_feed_sql="select count(*) as feedbacktotal from feedback where feedback_to=".$row['user_id'];
thanks in advance the else if($_POST) is line 18 btw

 

You need curly brackets around your if statements, for example:

if(condition){
//Do this
}
else if(condition){
//do this
}
else{
//do this
}

PHP:

The only time you can omit the curly brackets, is if you are only going to use 1 statement only, but you are using many.

So basically your IF statement becomes this:

if($_GET){

$badwords = array("union", "select", "join", "concat", "from", "UNION", "SELECT", "JOIN", "CONCAT", "FROM");
$corrected = str_replace($badwords,"getalife",$_GET['item_id']);
$item_id = $corrected;
echo $item_id;
}
else if($_POST){

$badwords = array("union", "select", "join", "concat", "from", "UNION", "SELECT", "JOIN", "CONCAT", "FROM");
$corrected = str_replace($badwords,"getalife",$_POST['item_id']);
$item_id = $corrected;
echo $item_id;

$badwords = array("union", "select", "join", "concat", "from", "UNION", "SELECT", "JOIN", "CONCAT", "FROM");
$corrected = str_replace($badwords,"getalife",$_GET[mode]);
$mode = $corrected;
echo $mode;

}

PHP:

assuming thats where the else if ends.