PHP Session variables not persisting - php

Question

I'm creating a site that uses sessions to store login details - I know its a bad security practice but that'll be dealt with later; for now I just need to fix this issue. Page 1 gets the login details from a login form and stores them in a session. Page 2 is meant to display those variables, but I get these errors when trying to access the variables:
Notice: Undefined index: email in /customers/0/4/0/my-domain.com/httpd.www/upload-photo.php on line 10
Notice: Undefined index: password in /customers/0/4/0/my-domain.com/httpd.www/upload-photo.php on line 11
Here is the code - I've left off the unrelated parts:
Page 1
session_start();
var_dump($_SESSION);
ini_set('display_errors',1);
error_reporting(E_ALL);
// Just logged in
if($_POST["email"] != "" || $_POST["password"] != ""){
$email = strtolower($_POST["email"]);
$password = md5($_POST["password"]);
$_SESSION["email"] = $email;
$_SESSION["password"] = $password;
//echo "setting details from http post";
}else{
// Just redirected to this page
$email = $_SESSION["email"];
$password = $_SESSION["password"];
}
And page 2 where I'm getting the errors mentioned above:
session_start();
ini_set('display_errors',1);
error_reporting(E_ALL);
var_dump($_SESSION);
$_SESSION["advert"] = $_GET['id'];
echo $_SESSION["email"];
echo $_SESSION["password"];
I've searched SO and have made sure there are no spaces or whatever before my session_start();
By the way, if it helps my domain company that I'm using is One.com

Answer 1

$_SESSION["email"] and $_SESSION["password"] are set in the if, so in the case it is skipped you get this undefined indexes error (as elements with this indexes were not defined anywhere before).To get rid of this Notice you can use isset() function(also use it to validate $_POST user input). Example :
echo isset($_SESSION["email"]) ? $_SESSION["email"] : 'There is no element with key "email"';
P.S. Validating your POST input :
if(isset($_POST["email"]) && isset($_POST["password"])){}

Answer 2

Change condition to:
if(isset($_POST['email']) && isset($_POST['password'])){
//do login
}
else {
echo " Plese enter email and password";
}
For full:
Login.php
<?php
//here must be totaly clear, nothing can't be here
session_start();
if(isset($_POST['email']) && isset($_POST['password'])){
$_SESSION['email'] = $_POST['email'];
$_SESSION['password'] = $_POST['password'];
}
else {
echo "Please enter email and password";
}
//here must be form to login
Logged.php:
<?php
//here must be totaly clear, nothing can't be here
session_start();
if(!isset($_SESSION['email']) && !isset($_SESSION['password'])){
header("Location: Login.php?err=Please login to use members area");
}
else {
echo "You are logged in as:". $_SESSION['email'];
}

Answer 3

I solved the problem. When I was on one page I was on www.domain.com/page1 but when I was on the other page there was no www - domain.com/page2. This meant that session variables were not persisting. To fox this, I need to edit the htaccess file to redirect to www if there is no www in the URL.