Question on Sessions

[shiyam198]

John | Please use [code], [php], and [quote] tags when appropriate.
Hi,

First time using sessions.

I created a Userlogin functionality to the website I am creating.
I had the index.php page where it takes the username and password and checks against a file where I have the password and when it is correct assigns the username to a variable called "logged".

PHP Code:

$_SESSION["logged"]=$_POST["username"]; 


Now, in all the pages I have, i have included the following code segment,

PHP Code:

<?php
session_start(); /// initialize session
include("passwords.php");
check_logged(); /// function checks if visitor is logged. If user is not logged the user is redirected to login.php page
?>

where the passwords.php is

PHP Code:

<?
$USERS["user1"] = "pass1";
$USERS["user2"] = "pass2";
$USERS["user3"] = "pass1";
function check_logged(){
     global $_SESSION, $USERS;
     if (!array_key_exists($_SESSION["logged"],$USERS)) {
          header("Location: index.php");
     };
};
?>

Question:

In those pages I already had two includes so I uncluded the code segment after that.

Like this:

PHP Code:

<?php
include("top.php");
include("conn.php");

session_start(); /// initialize session
include("passwords.php");
check_logged(); /// function checks if visitor is logged. If user is not logged the user is redirected to login.php page
?>

When I did that, I got the following error message.

"session_start(): Cannot send session cache limiter - headers already sent

(output started at top.htm............"

I took the code segment out from all the pages and put on top of top.php, it works fine.

Why does that session_start() should be on top the file. Or is it some other problem caused this error ?

Thanks for your time
Shiyam
John | Please use [code], [php], and [quote] tags when appropriate.

[John]

Originally Posted by shiyam198

When I did that, I got the following error message.
(output started at top.htm............"

I took the code segment out from all the pages and put on top of top.php, it works fine.

Why does that session_start() should be on top the file. Or is it some other problem caused this error ?

The cache limiter warning is issued when content is outputted prior to the session_start() directive being called. That said, it must be placed at the top of the page (or before you output any content). I'm not sure the reasoning behind it - I just accepted it.