登錄無法正常工作PHP MySQL

Question

我正在嘗試修復我的登錄頁面...

通過重定向，它在login.php上可以正常工作，但在索引上，即使會話為空，它也不會重定向。 有指針嗎？ 我對此並不陌生，所以如果真的很明顯，請原諒我。

 <?php
 require_once('../includes/config.php');
 session_start();
 if(!isset($_SESSION['loggedin']) && $_SESSION['loggedin']=='no'){
      // not logged in
      header("location: login.php");
      exit();
 } else {
      $_SESSION['loggedin'] = 'yes';
 }
 ?>
 <?php

 include("../includes/config.php");
 $error = NULL;
 $atmpt = 1;

 if (!isset($_SESSION)) {
      session_start();
 }

 if(isset($_SESSION['loggedin']) && $_SESSION['loggedin']=='yes'){
      // logged in
      header("location: index.php");
      exit();
 }

 if(isset($_POST['login']))
 {

 /* get username and password */
 $username = $_POST["username"];
 $password = $_POST["password"];

 /* MySQL Injection prevention */
 $username = mysqli_real_escape_string($mysqli, stripslashes($username));
 $password = mysqli_real_escape_string($mysqli, stripslashes($password));

 /* check for user in database */
 $query = "SELECT * FROM admin_accounts WHERE username = '$username' AND password =      '$password'"; // replace "users" with your table name
 $result = mysqli_query($mysqli, $query);
 $count = $result->num_rows;
 if($count > 0){
      //successfully logged in
      $_SESSION['username']=$username;
      $_SESSION['loggedin']='yes';
      $error .= "<div class='alert alert-success'>Thanks for logging in! Redirecting      you..</div>";
      header("refresh:1;url=index.php");
 } else {
      // Login Failed
      $error .=  "<div class='alert alert-danger'>Wrong username or password..</div>";
      $_SESSION['loggedin']='no';
      $atmpt = 2;
 }
 } 

 ?>

Answer 1

線

session_start();

應該是php腳本中的第一行。

Answer 2

只需修改前三行。

由於session_start()應該放在任何輸出都放在瀏覽器之前（甚至是空格）。

<?php    
session_start();
require_once('../includes/config.php');
if (empty($_SESSION['loggedin']) && $_SESSION['loggedin']=='no') {

...