redirecting user to another page using header() - php

Question

I've looked everywhere and tried all solutions but it's still not getting me anywhere. Here's my code:
<?php
if(!empty($_SESSION['LoggedIn']) && !empty($_SESSION['Username']))
{
header('Location: /public_html/index.php');
exit;
}
elseif(!empty($_POST['username']) && !empty($_POST['password']))
{
$username = mysql_real_escape_string($_POST['username']);
$password = md5(mysql_real_escape_string($_POST['password']));
$checklogin = mysql_query("SELECT * FROM users WHERE Username = '".$username."' AND Password = '".$password."'");
if(mysql_num_rows($checklogin) == 1)
{
$row = mysql_fetch_array($checklogin);
$email = $row['EmailAddress'];
$_SESSION['Username'] = $username;
$_SESSION['EmailAddress'] = $email;
$_SESSION['LoggedIn'] = 1;
header('Location: /public_html/index.php');
exit;
}
else
{
echo "<h1>Error</h1>";
echo "<p>Sorry, your account could not be found. Please click here to try again.</p>";
}
}
?>
When I upload this into my server and login it brings me to a blank php page. What am I doing wrong with this code? I've tried using " instead of ' . I'm trying to redirect the user to a page outside of the folder hence the "/public_html/". Any help would be much appreciated.

Answer 1

if outside the folder than use
header("Location:../public_html/index.php");

Answer 2

Starting your URL with / and followed with the folder name means, you want to go to the top/root directory, and followed with the folder name you've specified.
For example:
Getting to /public_html means you're redirecting to http://www.example.com/public_html which I believe to be non-existance in your case
To get around this problem, do this:
add a double dot: ..
Getting to ../public_html means you're redirecting from http://www.example.com/some_project/some_folder/ to http://www.example.com/some_project/public_html/ (for example).
refer to Vicky's answer,
header("Location:../public_html/index.php");
exit();
and do not forget to add the exit(); in the end.
edit: Please cease using the ancient PHP-MySQL. There's a better alternative for you to use, for your own safety:
PHP MySQLi
PHP PDO MySQL