Strange header(&quot;&quot;) problem

Strange header("") problem

Jeremias

If I use this code

 	$query="SELECT C_vak, Vak from vakken";
 	$result=mysql_query($query);

print("<center>");
print("<form method=\"post\" action=\"".$_SERVER['PHP_SELF']."\">");  
print("<table>"); 

while($vak=mysql_fetch_array($result))
{
	print("<tr><td align=\"left\" width=\"70\"><input name=\"add\" type=\"submit\" value=\"$vak[0]\"></td><td>$vak[1] &nbsp; \n</TD>\n");		
	print("<td align=\"right\">\n");
	print("<SELECT NAME=\"datum\">\n");	
	print("<OPTION VALUE=\"SoSe 2002\">SoSe 2002\n");
	print("<OPTION VALUE=\"WiSe 2002\">WiSe 2002\n");
	print("<OPTION VALUE=\"SoSe 2003\">SoSe 2003\n");
	print("<OPTION VALUE=\"WiSe 2003\">WiSe 2003\n");
	print("<OPTION VALUE=\"SoSe 2004\">SoSe 2004\n");
	print("<OPTION VALUE=\"WiSe 2004\">WiSe 2004\n");
	print("<OPTION VALUE=\"SoSe 2005\">SoSe 2005\n");
	print("<OPTION VALUE=\"WiSe 2005\">WiSe 2005\n");
	print("</SELECT>");
	print("</td></tr>\n");
}	
print ("</table>");
print ("</center>");
print ("</form>");

$matr=$_SESSION["valid_id"];
if (isset ($_POST['add']))
{	$vakcode=$_POST['add'];

	$query="INSERT INTO exaam (Matrikkelnr, Code_V, Code_Ex) Values ('$matr', '$vakcode', 'none')";

	if (!mysql_query($query))
	{
		echo "<P>Sorry maar de gegevens konden niet toegevoegd worden aan de database, neem contact op met de Webmaster</p>";
	}
	else
	{
		header("Location: edit.php");
	}
}	
?>

I get the following error:
Warning: Cannot modify header information - headers already sent by (output started at c:\program files\easyphp1-7\www\addsubjects.php:63) in c:\program files\easyphp1-7\www\addsubjects.php on line 89

If I use this code it works:

 	$query="SELECT C_vak, Vak from vakken";
 	$result=mysql_query($query);

print("<center>");
print("<form method=\"post\" action=\"".$_SERVER['PHP_SELF']."\">");  
print("<table>"); 

while($vak=mysql_fetch_array($result))
{
	//print("<tr><td align=\"left\" width=\"70\"><input name=\"add\" type=\"submit\" value=\"$vak[0]\"></td><td>$vak[1] &nbsp; \n</TD>\n");		
	print("<tr><td align=\"left\" width=\"70\"><input name=\"add\" type=\"submit\" value=\"$vak[0]\"></td><td>$vak[1]\n</TD></tr>");
	/*print("<td align=\"right\">\n");
	print("<SELECT NAME=\"datum\">\n");	
	print("<OPTION VALUE=\"SoSe 2002\">SoSe 2002\n");
	print("<OPTION VALUE=\"WiSe 2002\">WiSe 2002\n");
	print("<OPTION VALUE=\"SoSe 2003\">SoSe 2003\n");
	print("<OPTION VALUE=\"WiSe 2003\">WiSe 2003\n");
	print("<OPTION VALUE=\"SoSe 2004\">SoSe 2004\n");
	print("<OPTION VALUE=\"WiSe 2004\">WiSe 2004\n");
	print("<OPTION VALUE=\"SoSe 2005\">SoSe 2005\n");
	print("<OPTION VALUE=\"WiSe 2005\">WiSe 2005\n");
	print("</SELECT>");
	print("</td></tr>\n");*/
}	
print ("</table>");
print ("</center>");
print ("</form>");

$matr=$_SESSION["valid_id"];
if (isset ($_POST['add']))
{	$vakcode=$_POST['add'];

	$query="INSERT INTO exaam (Matrikkelnr, Code_V, Code_Ex) Values ('$matr', '$vakcode', 'none')";

	if (!mysql_query($query))
	{
		echo "<P>Sorry maar de gegevens konden niet toegevoegd worden aan de database, neem contact op met de Webmaster</p>";
	}
	else
	{
		header("Location: edit.php");
	}
}	
?>

Can someone explain me what the dropboxes have to do with the header command ???

thx,
Jeremias

Weedpacket

Yes; headers cannot be sent after any output is generated - that includes the HTML for the drop boxes - it also includes the <html> tag itself and even anything that goes before the <html> tag.

Headers go at the head of the response that the server sends back to the client (hence the name) - if they went anywhere else they wouldn't be headers any more. They tell the client what to do with the content of the response, so the client pretty much needs them all before it starts working on the content that follows.

It's best if you rearrange your program so that you send all the headers you need to send before you send anything else.

Besides; if you're sending a Location: header, there's no point sending them anything else on that page anyway, is there? You're just putting extra load on the server, on your connection, on the client's connection, and on the client.

Jeremias

Thx for the reply, I'll see what I can do with your answer. It doesn't look easy but that doesn't mean it can't be solved.

Anyhow if can't figure it out myself I'll come back and ask more questions.

Jeremias

I don't totally understand what you are saying, what is the difference between this output

    while($vak=mysql_fetch_array($result)) 
    {      

      print("<tr><td align=\"left\" width=\"70\"><input name=\"add\" type=\"submit\" value=\"$vak[0]\"></td><td>$vak[1]\n</TD></tr>"); 
   }

and this output

    while($vak=mysql_fetch_array($result)) 
    { 
        print("<tr><td align=\"left\" width=\"70\"><input name=\"add\" type=\"submit\" value=\"$vak[0]\"></td><td>$vak[1] &nbsp; \n</TD>\n");         

        print("<td align=\"right\">\n"); 
        print("<SELECT NAME=\"datum\">\n");     

        print("<OPTION VALUE=\"SoSe 2002\">SoSe 2002\n"); 
        print("<OPTION VALUE=\"WiSe 2002\">WiSe 2002\n"); 
        print("<OPTION VALUE=\"SoSe 2003\">SoSe 2003\n"); 
        print("<OPTION VALUE=\"WiSe 2003\">WiSe 2003\n"); 
        print("<OPTION VALUE=\"SoSe 2004\">SoSe 2004\n"); 
        print("<OPTION VALUE=\"WiSe 2004\">WiSe 2004\n"); 
        print("<OPTION VALUE=\"SoSe 2005\">SoSe 2005\n"); 
        print("<OPTION VALUE=\"WiSe 2005\">WiSe 2005\n"); 
        print("</SELECT>"); 
        print("</td></tr>\n"); 
    }

Jeremias