Why cant i re-direct users!

[nmyster]

I am making a blog, it allows for a user to read stories and an admin to add, edit and delete stories. What i want to do is put a login page if the user has not already...

What i do is if a user accesses the page that is for admins, and they dont have access (a cookie thats created when they login) then it will re-direct them to the login page...

When i try and re-direct the user, using the code below:
<?php
$cookie = $_COOKIE["auth"];
if (!$cookie =="denied")
{
header("Location:./loginpage.php");
}
?>

i get the error: "Warning: Cannot modify header information - headers already sent by etc"

What do i do to fix this error!!!

[visionstudio]

Headers are sent to the browser before any content. The error message suggests the you have outputted content to the browser before the header.

Make sure that you dont have anything printed to the page before the header.

An alternative method would be to use output control.

http://www.php.net/manual/en/intro.outcontrol.php

Adding <?php ob_start(); ?> to the very top of your page should resolve the issue.

[Alan]

Originally Posted by visionstudio

Headers are sent to the browser before any content. The error message suggests the you have outputted content to the browser before the header.

Make sure that you dont have anything printed to the page before the header.

An alternative method would be to use output control.

http://www.php.net/manual/en/intro.outcontrol.php

Adding <?php ob_start(); ?> to the very top of your page should resolve the issue.

You will have to call ob_clean(); just before the header function. Also, you should call exit(); after the header function, just to avoid any further code execution before the redirection takes place.

PHP Code:

<?php
ob_start(); // Creates a new output buffer

echo 'oh oh... here\'s some text.'; // Goes into the buffer rather than being sent to the client

if($someCondition)
{
    ob_clean(); // Deletes the contents of the buffer

    header('Location: http://www.anothersite.com'); // Redirection
    exit();
}

echo 'There was no redirection.';

ob_end_flush(); // Sends the contents of the buffer to the client (Implicit but you should stick it in anyway)
exit();
?>

[mtimofiiv]

There is also another possibility.

PHP Code:

<?php
$cookie = $_COOKIE["auth"];
if (!$cookie =="denied")
{
header("Location:./loginpage.php");
}
?>

is there a space (the SPACE character I mean) after the <?php and BEFORE the new line? If so try removing this. This is a well known culprit that causes those exact header errors.