登录页面看起来像没有重定向到下一页如何解决这个问题？

Question

登录页面看起来像没有重定向到下一页如何解决这类问题？登录页面看起来像没有重定向到下一页，仍然坚持index.php页面如何解决这个错误....我认为会议是问题？

的index.php

<?php include('header.php'); ?> 
<?php include('navbar.php'); ?> 
    <div class="container"> 
     <div class="margin-top"> 
      <div class="row"> 
      <div class="span12"> 

       <div class="login"> 
       <div class="log_txt"> 
       <p><strong>Please Enter the Details Below..</strong></p> 
       </div> 
         <form class="form-horizontal" method="POST"> 
           <div class="control-group"> 
            <label class="control-label" for="inputEmail">Username</label> 
            <div class="controls"> 
            <input type="text" name="username" id="username" placeholder="Username" required> 
            </div> 
           </div> 
           <div class="control-group"> 
            <label class="control-label" for="inputPassword">Password</label> 
            <div class="controls"> 
            <input type="password" name="password" id="password" placeholder="Password" required> 
           </div> 
           </div> 
           <div class="control-group"> 
            <div class="controls"> 
            <button id="login" name="submit" type="submit" class="btn"><i class="icon-signin icon-large"></i>&nbsp;Submit</button> 
           </div> 
           </div> 

           <?php 
           if (isset($_POST['submit'])){ 
           session_start(); 

           $username = $_POST['username']; 
           $password = $_POST['password']; 
           $query = "SELECT * FROM users WHERE username='$username' AND password='$password'"; 
           $result = mysqli_query($dbcon, $query)or die(mysql_error()); 
           $num_row = mysqli_num_rows($result); 
            $row=mysql_fetch_array($result); 
            if($num_row > 0) { 
             header('location:../admin_uplbcdc/dashboard.php'); 
           $_SESSION['id']=$row['user_id']; 
            } 
            else{ ?> 

           <div class="alert alert-danger">Access Denied</div>  
           <?php 
           }} 
           ?> 
         </form> 

       </div> 
      </div>  
      </div> 
     </div> 
    </div> 
<?php include('footer.php') ?> 

dashboard.php

<?php require_once('../db/dbcon.php'); ?> 
<?php include('../admin_uplbcdc/session.php'); ?> 
<?php include('../admin_uplbcdc/header_2.php'); ?> 
<?php include('../admin_uplbcdc/navbar.php'); ?> 
    <div class="container"> 
     <div class="margin-top"> 
      <div class="row"> 
        <?php include('../admin_uplbcdc/head.php'); ?> 
       <div class="span2"> 
        <?php include('../admin_uplbcdc/sidebar.php'); ?> 
       </div> 
       <div class="span10" align="center"> 
       <br/> <br/> 
        <?php include('../admin_uplbcdc/slider.php'); ?> 
       </div>  
      </div> 

     </div> 
    </div> 
     <?php include('footer.php'); ?>  

Answer 1

正确设置错误报告和看到的警告。

以前有任何输出时，您不能启动会话或使用header重定向，请将session_start移动到PHP脚本的顶部。

的index.php

<?php include('header.php'); ?> 
<?php include('navbar.php'); ?> 
<?php 

session_start(); 

if (isset($_POST['submit'])) { 
    // all PHP code goes here 
} 

?> 

HTML goes here