Php 记录登录条目和会话状态

如何记录登录条目和会话状态？我一直在寻找源代码和想法，但有些我不懂。我想通过PHP问一个简单的代码。我有一个可以登录用户但不需要MySql数据库的代码，我想知道如何记录登录条目和连接PHP登录代码的会话状态。或者如果您有其他需要MySql数据库的选项代码

代码如下：

“CONFIG.PHP”

“INDEX.PHP”

“ADMIN.PHP”

始终将

session_start（）

作为

之后的第一条语句，我将把它放在哪里？它是HTML-因此您可以将它放在HTML代码中（例如，任何其他HTML标记可以放在任何地方），或者可以在PHP代码块中回显它：
echo”“测试它，用它做实验。请注意，许多人会告诉你不要使用这个指令，但是（就像任何事情一样）保持谨慎，尽可能多地学习可以让你做很多事情。“每个人”并不总是正确的如何记录用户的登录条目和会话状态？用户现在可以登录，但我仍然需要一个代码，记录用户注销后的登录条目。什么是会话状态？会话启动（）是否有会话状态代码？
<?php
$user = "admin";
$pass = "password";
?>

<?php
include("config.php");

// Check form if is submited
if(isSet($_POST['trimite'])) {
// Check if user is equal with username and  password from config.php
if($_POST['user'] != $user || $_POST['pass'] != $pass) {
echo "Sorry, your data is invalid";
} else {
// Open the session for store user logged
session_start();
// Setting the session
$_SESSION['logat'] = "da";
// Redirecting user to admin page if is logged
Header('Location: admin.php');
}
} else {
// Form
echo '<form action="" method="post">
Username: <input type="text" name="user">
Password: <input type="password" name="pass">
<input type="submit" name="trimite">
</form>';
}
?>

<?php
include("config.php");
// Start session
session_start();

// Check if user is logged and existing session
if(isset($_SESSION['logat'])) {
// Content for user logged
echo "Welcome ".$user." :) - <a href='logout.php'>Logout</a>";
} else {
// Redirecting to login page
Header("Location: ./");
}
?>

<?php
    session_start();
    include("config.php");

    // Check form if is submited
    if( isSet($_POST['user']) ) {
        // Check if user is equal with username and  password from config.php
        if($_POST['user'] != $user || $_POST['pass'] != $pass) {
            echo "Sorry, your data is invalid";
        } else {
            // Open the session for store user logged
            // Setting the session
            $_SESSION['logat'] = "da";
            $_SESSION['username'] = $_POST['user'];
            // Redirecting user to admin page if is logged
            header('Location: admin.php');
        }
    } else {
        // Form
        $out = '
            <form action="" method="post">
                Username: <input type="text" name="user">
                Password: <input type="password" name="pass">
                <input type="submit" name="trimite">
            </form>
        ';
        echo $out;
    }
?>

<?php
    // Start session
    session_start();

    include("config.php");

    // Check if user is logged and existing session
    if(isset($_SESSION['logat'])) {
        // Content for user logged
        echo "Welcome ".$_SESSION['username']." :) - <a href='logout.php'>Logout</a>";
    } else {
        // Redirecting to login page
        header("Location: ./");
    }
?>

<meta http-equiv="refresh" content="0;url=http://example.com">