Unable to logout session in PHP - php

Question

I tried a login and logout function in a signin bootstrap theme and it worked fine. But am not able to logout the session in my other tenplate when I use the same code which I used previously which worked. I tried all most all the solutions found in internet. I am getting a blank page when I click on Logout link.
login.php
<?php
session_start();
if (!empty($_SESSION['login_user'])) {
header('location:index.php');
}
?>
---html code---
<?php
define('DB_SERVER', 'localhost');
define('DB_USERNAME', 'root');
define('DB_PASSWORD', '');
define('DB_DATABASE', 'foodchain');
$db = mysqli_connect(DB_SERVER,DB_USERNAME,DB_PASSWORD,DB_DATABASE);
if($_SERVER["REQUEST_METHOD"] == "POST") {
$myusername = mysqli_real_escape_string($db,$_POST['email']);
$mypassword = mysqli_real_escape_string($db,$_POST['password']);
$sql = "SELECT email,password FROM user_register WHERE email='$myusername' and password = '$mypassword'";
$result = mysqli_query($db,$sql);
$row = mysqli_fetch_array($result,MYSQL_ASSOC);
$count = mysqli_num_rows($result);
if($count == 1) {
$_SESSION['login_user'] = $myusername;
header('Location:index.php');
}else {
$logmsg = "Invalid Username or Password";
}
}
?>
check_login.php
<?php
session_start();
if (!isset($_SESSION['login_user']) || empty($_SESSION['login_user'])) {
header('location:login.php');
}
?>
logout.php
<?php
session_start();
session_destroy();
header("Location:login.php");
die();
?>
index.php
<?php
include('check_login.php');
?>
Its perfectly working when I don't use the template(downloaded from some website), or when I use the bootsrap signin template.

Answer 1

You really should provide us with some source code, links to things that you've tried, what you've previously tried, what errors you received, etc. From what I can gather, you're looking for a logout page using sessions? Here's what I've got.
<?php
session_start();
session_destroy();
header('Location: ..');
?>

Answer 2

The key part is setting $_SESSION to an empty array.
From http://php.net/manual/en/function.session-destroy.php:
<?php
// Initialize the session.
// If you are using session_name("something"), don't forget it now!
session_start();
// Unset all of the session variables.
$_SESSION = array();
// If it's desired to kill the session, also delete the session cookie.
// Note: This will destroy the session, and not just the session data!
if (ini_get("session.use_cookies")) {
$params = session_get_cookie_params();
setcookie(session_name(), '', time() - 42000,
$params["path"], $params["domain"],
$params["secure"], $params["httponly"]
);
}
// Finally, destroy the session.
session_destroy();
?>