[PHP] Need help on Error

Seachmall · 22-01-2008 10:15pm #1

I'm getting an error in my php script. It works fine on localhost but the error occurs when I upload it.

[PHP]Warning: Cannot modify header information - headers already sent by (output started at

\path\to\file\login.php:10) in

\path\to\file\login.php on line 35[/PHP]

I've done a bit of googling and found the error is normally caused by whitespace before session_start() however there is no whitespace in mine.

The code
[PHP]<?PHP // <<Line 10
if(isset($_POST) && isset($_POST)){

require('library.php');

$user = $_POST;
$pass = $_POST;

$connection = new connectDb;
$connection->connect();
$connection->select_db();

$login = new login;
$login->escape_input($pass,$user);
$login->check_user();
$login->check_pass();

if($login->logged()=='True'){
if(!isset($_SESSION)){
$_SESSION='admin';
}
header('location: newpage.php'); // <<Line 35
}else{
echo 'Invalid Loggin';
}
$connection->disconnect();

}[/PHP]

Any help appreciated.

stevenmu · 22-01-2008 11:02pm

Don't know much about php, but in ASP that error usually happens because you've output something before you try and redirect to a new page. Looking at your line 35 that looks like what you're doing, so you need to find where you're outputting something. What do you have before line 10?

decob · 22-01-2008 11:09pm

where are you calling session_start() ??? is it at the very top of that page.?

seamus · 22-01-2008 11:09pm

Well, what's before line 10? If there's anything whatsoever output before the cookies, it won't work.

If you're going to use sessions, the first 2/5 characters of line 1 of your script must be
<?php

Remember that anything outside of the <?php ?> tags will be output to the browser. So if that's line 10 of your script, there is something being output.

Seachmall · 22-01-2008 11:51pm

The first 9 lines
[PHP]<?PHP
session_start();
?>
<html>
<head>
<title></title>
<link rel='stylesheet' type='text/css' href='../Styles/adminstyle.css'/>
</head>
<body>[/PHP]

The form is on the same page (underneath were the last snippet I gave you stopped) and it refreshes to that page which checks if the form login validates. Could that be a factor? The $_POST is being sent before the $_SESSION?

seamus · 23-01-2008 12:03am

D'oh! Totally missed your call to header();

header() has the same restrictions as setting sessions and cookies. If you've already output anything to the browser, you can't call header()

If you need to use header to redirect someone, do all your validation/processing before you output any HTML.

Also remember to call die() after calling header(). This will stop the script from executing. If you don't call die(), something may get executed that you didn't want, e.g.
[php]
<?php

if($_COOKIE != "admin") {
header("location: error.php"); //The browser gets redirected here
}

mysql_query("DROP TABLE my_really_important_data"); //This line still gets executed by the server.

?>[/php]

Seachmall · 23-01-2008 12:16am

So shift all my validation above the html tags and add die() after my header()?

seamus · 23-01-2008 12:18am

Yep.

Seachmall · 23-01-2008 12:28am

Thank you so much. Its so fusterating when you work on something offline, go to upload it and it breaks. The other day I found out my account didn't support PHP 5 causing a crash, then this! I hope thats the last of it.

Thanks again

.

louie · 24-01-2008 9:56am

add this code at the very top of your pages and should sort out your problem:
[php]
<?php
session_start(); // Initialize session data
ob_start(); // Turn on output buffering
?>
[/php]
also before calling the header add
[php]
ob_clean();
header("location: error.php"); //The browser gets redirected here
[/php]

[PHP] Need help on Error

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