我知道我的代码非常初学者，因为我刚开始使用 php。一开始很抱歉
我已经阅读堆栈其他问题和答案
警告：session_destroy()：试图销毁未初始化的会话
所有答案都提到我需要在使用之前使用session_start()
session_destroy();
但他们没有解释为什么会出现这个警告，即使我已经使用了session_start()我只是想登录然后仪表板页面出现，用户可以点击注销按钮注销
整个应用程序工作正常，唯一的问题是当我单击dashboard.php 中的注销按钮时，它会转到注销页面并显示上面提到的警告
登录.php
<?php
session_start();
}
?>
<!DOCTYPE html>
<html>
<head>
<title>Login Page</title>
<link rel="stylesheet" type="text/css" href="style.css">
</head>
<body>
<div class="header">
<h1 align="center">Login</h1>
</div>
orm action="" method="post">
<table align="center">
<tr>
<td align="right"><input type="email" name="email" placeholder="Email" required></td>
<td class="s1">*</td>
</tr>
<tr>
<td align="right"><input type="password" name="pass" placeholder="Password" pattern="(?=.*\d)(?=.*[a-z])(?=.*[A-Z]).{8,12}" title="Must contain at least one number and one uppercase and lowercase letter, and at least 8 or more characters" required></td>
<td class="s1">*</td>
</tr>
<tr>
<td align="right"><input type="submit" value="Login"><td>
</tr>
</table>
<p align="center"><strong>Or</strong></p>
<p align="center">Create New acount <strong><input type="button" value="Sign Up" onclick="location.href='sign_up.php'"></strong></p>
<br>
<br>
<br>
<br>
<br>
<div class="footer">
<p><span class="s1">*</span> indicates mandatory feild<p>
</div>
</body>
</html>
<?php
require 'connection.php'; // connection
if($_SERVER['REQUEST_METHOD'] === 'POST')
{
$email = $_POST['email'];
$pass = $_POST['pass'];
// getting username from database and storing into session variable
/// $sql =mysqli_query($conn,"SELECT name FROM users WHERE email='$email'");
$sql1 = mysqli_fetch_assoc($sql);
$user_name = $sql1['name'];
// setting session variables
$_SESSION['user_name']= $cookie_name;
$_SESSION['timeout']=time();
// check email exists or not
$query=mysqli_query($conn,"SELECT email FROM users WHERE email='$email'");
if(mysqli_num_rows($query) > 0)
{
//check email and password correct or not
$query1=mysqli_query($conn,"SELECT email, password FROM users WHERE email='$email' AND password='$pass'");
if(mysqli_num_rows($query1) > 0)
{
// login success
header("location:dashboard.php");
// ----> alternative way to redirect to dashboard.php
/*echo "<script type='text/javascript'>
window.location.href = 'dashboard.php'
</script>";*/
}
else
{
// incorrect password
echo "<p align='center' style='color:#ff6262'>your password is incorrect!<br>Please try again</p>";
}
}
else
{
// email not exist
echo "<p align='center' style='color:#ff6262'><b>Email you are entering does not exist in our database<br></b></p>";
}
}
?>
仪表盘.php
<?php
session_start();
?>
<!DOCTYPE html>
<html>
<head>
<title>
<?php
require 'connection.php';
echo $_SESSION['user_name'];
?>
</title>
<link rel="stylesheet" type="text/css" href="style.css">
</head>
<body>
<div class="header"> <h1 align="center"><?php echo "Welcome: ".ucfirst($_SESSION['user_name']); ?></h1>
</div>
<table>
<tr>
<td align="right">Change User Name:</td><td><input type="button" onclick="location.href='user.php'" value="click here"></td>
</tr>
<tr></tr>
<tr>
<td align="right">Change Password:</td><td><input type="button" onclick="location.href='pass.php'" value="click here"></td>
</tr colspan="2">
<tr><td align="right"><input type="button" value="Logout" onclick="location.href='logout.php'"></td></tr>
</table>
</body>
</html>
<?php
if (isset($_SESSION['timeout']) && (time() - $_SESSION['timeout'] > 60)) {
session_unset(); // unset $_SESSION variable for the run-time
session_destroy(); // destroy session data in storage
header("location:logout.php");
}
$_SESSION['timeout'] = time();
?>
登出.php
<?php
session_start();
?>
<?php
session_unset();
if(!session_unset())
{
echo "session not unset";
}
else {
echo "session unset";
}
session_destroy();
if(!session_destroy())
{
echo "session not destroyed";
}
else {
echo "session destroyed";
}
//header(location:login.php);
?>
其他人建议我使用 cookie，但我不知道如何将 cookie 与任何可以提供帮助的人联系起来。
你跑了session_destroy()两次！这会导致您的错误。if语句运行的代码后的最初session_destroy()。
你也在这样做session_unset()，同样的修复。
这是导致问题的代码（第二个session_destroy()返回 false）：
session_destroy(); // returns true
if(!session_destroy()) // returns false, because the session is already destroyed.
{
echo "session not destroyed"; // this gets ran
}
else {
echo "session destroyed";
}
您可以更改为此，以解决您的错误。
if(!session_destroy())
{
echo "session not destroyed";
}
else {
echo "session destroyed";
}
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