用戶登錄后如何將登錄按鈕更改為注銷 PHP

Question

我的登錄按鈕在用戶登錄后保持登錄狀態。下面的代碼是我嘗試過的。

<?php 
        //session_start();
        if (isset($_SESSION['user_logged_in'])) {
            echo' <a href="logout.php"><input id="btnlogout" 
type="button" value="LOGOUT" class="log" /></a>';
        } else {
            echo '<a href="login.php"><input id="btnlogin" 
type="button" value="LOGIN" class="log" /></a>';
            echo '<a href="register.php"><input id="btnregistser" 
type="button" value="Register" class="reg" /></a>';
        }
        ?>

注銷.php

<?php
session_start();
unset($_SESSION['user_logged_in']);
session_destroy();
echo "You have logout successfully";
header("refresh:2;url=homepage.php");
?>

check.php（查看首頁1st php數據）

if ($username==$row['username'] && $password==$row['password']){
        session_start();
        //$_SESSION['username']=$username;
        $_SESSION['user_logged_in'] = true;
    echo "You have logged in successfully.";
    header("refresh:2;url=homepage.php");
    break;
    }
    else{   
        session_start();
        $_SESSION['username']=$username;
    header("Location:fail.php");
    }
        } 

我希望該按鈕可以更改為注銷按鈕，但它不起作用。

Answer 1

它應該看起來像這樣

<?php 
//session_start();
if (isset($_SESSION['user_logged_in'])) {
    echo' <a href="logout.php"><input id="btnlogout" type="button" value="LOGOUT" class="log" /></a>';
} else {
    echo '<a href="login.php"><input id="btnlogin" type="button" value="LOGIN" class="log" /></a>';
    echo '<a href="register.php"><input id="btnregistser" type="button" value="Register" class="reg" /></a>';
}
?>