如果我问一个对你们这些人来说可能很容易的问题，我会提前道歉。我的网站出现了一些错误。它适用于我的本地开发环境，但在我使用的托管平台（000webhost）上，我在以下页面中收到以下错误：
注册页面（pt-5-register.php） - 当我填写页面的所有细节时，我会收到以下错误：Warning: Cannot modify header information - headers already sent by (output started at /storage/ssd4/573/2779573/public_html/pt-5-register.php:1) in /storage/ssd4/573/2779573/public_html/pt-5-register.php on line 123。在“pt-5-register.php”文件中，我已经注意到发生错误的行。请留意第123行。Image of attempted registration - username: 1st.test
但是，当我登录数据库时，可以看到新创建的用户。我甚至为日志创建了一个脚本，它记录了时间和日期。时间和日期对应于我尝试注册的时间。不幸的是，用户名不会出现在数据库中。
然后我进入登录页面查看发生了什么，输入我'注册'的详细信息，并收到以下错误：
Notice: Undefined variable: link in /storage/ssd4/573/2779573/public_html/pt-5-login.php on line 47
Warning: mysqli_prepare() expects parameter 1 to be mysqli, null given in /storage/ssd4/573/2779573/public_html/pt-5-login.php on line 47
Warning: mysqli_stmt_close() expects parameter 1 to be mysqli_stmt, null given in /storage/ssd4/573/2779573/public_html/pt-5-login.php on line 105
Notice: Undefined variable: link in /storage/ssd4/573/2779573/public_html/pt-5-login.php on line 110
Warning: mysqli_close() expects parameter 1 to be mysqli, null given in /storage/ssd4/573/2779573/public_html/pt-5-login.php on line 110
在“pt-5-login.php”文件中，我注意到发生错误的行。注意第47,105和110行。
以下代码是发生此网站错误的网页。该网站的链接将根据要求发送。
请帮助，因为我相信我离完成此登录/注册系统并不远。
以下是配置页面的PHP代码“config.php”
<?php
/* Database credentials. Assuming you are running MySQL
server with default setting (user 'root' with no password) */
define("DB_SERVER", "localhost");
define("DB_USERNAME", "***********");
define("DB_PASSWORD", "***********");
define("DB_DATABASE", "***********");
// Attempt to connect to MySQL database
$connect = mysqli_connect(DB_SERVER, DB_USERNAME, DB_PASSWORD, DB_DATABASE);
// Check connection
if($connect === false)
{
die("ERROR: Could not connect. " . mysqli_connect_error());
}
?>
以下是注册页面的PHP / HTML代码“pt-5-register.php”
<!-- ----------------------------------------------------------------------- */
/* Taken from "Tutorial Republic - PHP MySQL Login System" -
/* ------------------------------------------------------------------------ -->
----PHP CODE----
<?php
// Include config file
require_once 'config.php';
// Define variables and initialize with empty values
$username = $password = $confirm_password = "";
$username_err = $password_err = $confirm_password_err = "";
// Processing form data when form is submitted
if($_SERVER["REQUEST_METHOD"] == "POST")
{
// Validate username
if(empty(trim($_POST["username"])))
{
$username_err = "Please enter a username.";
}
else
{
// Prepare a select statement
$sql = "SELECT id FROM users WHERE username = ?";
if($stmt = mysqli_prepare($connect, $sql))
{
// Bind variables to the prepared statement as parameters
mysqli_stmt_bind_param($stmt, "s", $param_username);
// Set parameters
$param_username = trim($_POST["username"]);
// Attempt to execute the prepared statement
if(mysqli_stmt_execute($stmt))
{
/* store result */
mysqli_stmt_store_result($stmt);
if(mysqli_stmt_num_rows($stmt) == 1)
{
$username_err = "This username is already taken.";
}
else
{
$username = trim($_POST["username"]);
}
}
else
{
echo "Oops! Something went wrong. Please try again later.";
}
}
// Close statement
mysqli_stmt_close($stmt);
}
// Validate password
if(empty(trim($_POST['password'])))
{
$password_err = "Please enter a password.";
}
elseif(strlen(trim($_POST['password'])) < 6)
{
$password_err = "Password must have atleast 6 characters.";
}
else
{
$password = trim($_POST['password']);
}
// Validate confirm password
if(empty(trim($_POST["confirm_password"])))
{
$confirm_password_err = 'Please confirm password.';
}
else
{
$confirm_password = trim($_POST['confirm_password']);
if($password != $confirm_password)
{
$confirm_password_err = 'Password did not match.';
}
}
// Check input errors before inserting in database
if(empty($username_err) && empty($password_err) && empty($confirm_password_err))
{
// Prepare an insert statement
$sql = "INSERT INTO users (username, password) VALUES (?, ?)";
if($stmt = mysqli_prepare($connect, $sql))
{
// Bind variables to the prepared statement as parameters
mysqli_stmt_bind_param($stmt, "ss", $param_username, $param_password);
// Set parameters
$param_username = $username;
$param_password = password_hash($password, PASSWORD_DEFAULT); // Creates a password hash
// Attempt to execute the prepared statement
if(mysqli_stmt_execute($stmt))
{
// Redirect to login page
header("location: pt-5-login.php"); // LINE 123 - ERROR OCCURRED
}
else
{
echo "Something went wrong. Please try again later.";
}
}
// Close statement
mysqli_stmt_close($stmt);
}
// Close connection
mysqli_close($connect);
}
?>
<!-- ----------------------------------------------------------------------------------- */
/* Temporary suspension of "Tutorial Republic - PHP MySQL Login System" Tutorial
/* ------------------------------------------------------------------------------------ -->
----HTML CODE----
<!doctype html>
<html>
<head>
<title>Learning Portal</title> <!-- CHANGE THESE IN ALL FILES RELATING TO THIS PROJECT! -->
<meta name="description" content="Learning Portal">
<meta name="keywords" content="Learning Portal EFREI">
<meta name="author" content="D.Jackson">
<link rel="stylesheet" type="text/css" href="NHS.css" media="screen">
<link rel="icon" type="image/ico" href="favicon.ico">
<link href="https://fonts(dot)googleapis(dot)com/css?family=Jura" rel="stylesheet">
</head>
<!-- <div> is to group block elements for CSS formatting -->
<body>
<div id="container">
<header><a href="pt-5-home.htm">Register</a>
</header>
<!-- The htm. above which would connect to the main page was originally
"mars.htm", then "NHS.htm" and is now called "pt-5-home.htm" -->
<!--
<div id="main">
<section>
<p>Please enter your details:
</p>
-->
<!-- ----------------------------------------------------------------------- */
/* Resuming "Tutorial Republic - PHP MySQL Login System"
https://www.tutorialrepublic.com/php-tutorial/php-mysql-login-system.php
/* ------------------------------------------------------------------------ -->
<!--
</head>
<body>
-->
<div class="wrapper">
<h2>Sign Up</h2>
<p>Please fill this form to create an account.</p>
<form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>" method="post">
<div class="form-group
<?php echo (!empty($username_err)) ? 'has-error' : ''; ?>">
<label>Username:<sup>*</sup></label>
<input type="text" name="username"class="form-control" value="<?php echo $username; ?>">
<span class="help-block"><?php echo $username_err; ?></span>
</div>
<div class="form-group
<?php echo (!empty($password_err)) ? 'has-error' : ''; ?>">
<label>Password:<sup>*</sup></label>
<input type="password" name="password" class="form-control" value="<?php echo $password; ?>">
<span class="help-block"><?php echo $password_err; ?></span>
</div>
<div class="form-group
<?php echo (!empty($confirm_password_err)) ? 'has-error' : ''; ?>">
<label>Confirm Password:<sup>*</sup></label>
<input type="password" name="confirm_password" class="form-control" value="<?php echo $confirm_password; ?>">
<span class="help-block"><?php echo $confirm_password_err; ?></span>
</div>
<div class="form-group">
<input type="submit" class="btn btn-primary" value="Submit">
<input type="reset" class="btn btn-default" value="Reset">
</div>
<p>Already have an account? <a href="pt-5-login.php">Login here</a>.</p>
</form>
</div>
</body>
</html>
以下是登录页面的PHP / HTML代码“pt-5-login.php”
<!-- ----------------------------------------------------------------------- */
/* Taken from "Tutorial Republic - PHP MySQL Login System"
/* ------------------------------------------------------------------------ -->
----PHP CODE----
<?php
// Include config file
require_once 'config.php';
// Define variables and initialize with empty values
$username = $password = "";
$username_err = $password_err = "";
// Processing form data when form is submitted
if($_SERVER["REQUEST_METHOD"] == "POST")
{
// Check if username is empty
if(empty(trim($_POST["username"])))
{
$username_err = 'Please enter username.';
}
else
{
$username = trim($_POST["username"]);
}
// Check if password is empty
if(empty(trim($_POST['password'])))
{
$password_err = 'Please enter your password.';
}
else
{
$password = trim($_POST['password']);
}
// Validate credentials
if(empty($username_err) && empty($password_err))
{
// Prepare a select statement
$sql = "SELECT username, password FROM users WHERE username = ?";
if($stmt = mysqli_prepare($link, $sql)) // LINE 47 - ERROR OCCURRED
}
{
// Bind variables to the prepared statement as parameters
mysqli_stmt_bind_param($stmt, "s", $param_username);
// Set parameters
$param_username = $username;
// Attempt to execute the prepared statement
if(mysqli_stmt_execute($stmt))
{
// Store result
mysqli_stmt_store_result($stmt);
// Check if username exists, if yes then verify password
if(mysqli_stmt_num_rows($stmt) == 1)
{
// Bind result variables
mysqli_stmt_bind_result($stmt, $username, $hashed_password);
if(mysqli_stmt_fetch($stmt))
{
if(password_verify($password, $hashed_password))
{
/* Password is correct, so start a new session and
save the username to the session */
session_start();
$_SESSION['username'] = $username;
header("location: welcome.php");
}
else
{
// Display an error message if password is not valid
$password_err = 'The password you entered was not valid.';
}
}
}
else
{
// Display an error message if username doesn't exist
$username_err = 'No account found with that username.';
}
}
else
{
echo "Oops! Something went wrong. Please try again later.";
}
}
// Close statement
mysqli_stmt_close($stmt); // LINE 105 - ERROR OCCOURED
}
}
// Close connection
mysqli_close($link); // LINE 110 - ERROR OCCOURED
}
}
?>
<!-- ----------------------------------------------------------------------------------- */
/* Temporary suspension of "Tutorial Republic - PHP MySQL Login System" Tutorial
/* ------------------------------------------------------------------------------------ -->
----HTML CODE----
<!doctype html>
<html>
<head>
<title>Learning Portal</title> <!-- CHANGE THESE IN ALL FILES RELATING TO THIS PROJECT! -->
<meta name="description" content="Learning Portal">
<meta name="keywords" content="Learning Portal EFREI">
<meta name="author" content="D.Jackson">
<link rel="stylesheet" type="text/css" href="NHS.css" media="screen">
<link rel="icon" type="image/ico" href="favicon.ico">
<link href="https://fonts(dot)googleapis(dot)com/css?family=Jura" rel="stylesheet">
</head>
<!-- <div> is to group block elements for CSS formatting -->
<body>
<div id="container">
<header><a href="pt-5-home.htm">Login</a>
</header>
<!-- The htm. above which would connect to the main page was originally
"mars.htm", then "NHS.htm" and is now called "pt-5-home.htm" -->
<!--
<div id="main">
<section>
<p>Please enter your details:
</p>
-->
<!-- ----------------------------------------------------------------------- */
/* Resuming "Tutorial Republic - PHP MySQL Login System"
https://www.tutorialrepublic.com/php-tutorial/php-mysql-login-system.php
/* ------------------------------------------------------------------------ -->
<body>
<div class="wrapper">
<h2>Login</h2>
<p>Please fill in your credentials to login.</p>
<form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>" method="post">
<div class="form-group <?php echo (!empty($username_err)) ? 'has-error' : ''; ?>">
<label>Username:<sup>*</sup></label>
<input type="text" name="username"class="form-control" value="<?php echo $username; ?>">
<span class="help-block"><?php echo $username_err; ?></span>
</div>
<div class="form-group <?php echo (!empty($password_err)) ? 'has-error' : ''; ?>">
<label>Password:<sup>*</sup></label>
<input type="password" name="password" class="form-control">
<span class="help-block"><?php echo $password_err; ?></span>
</div>
<div class="form-group">
<input type="submit" class="btn btn-primary" value="Submit">
</div>
<p>Don't have an account? <a href="pt-5-register.php">Sign up now</a>.</p>
</form>
</div>
</body>
</html>
答案 0 :(得分：1)
在注册脚本中，第一行是：
<!-- ----------------------------------------------------------------------- */
/* Taken from "Tutorial Republic - PHP MySQL Login System" -
/* ------------------------------------------------------------------------ -->
----PHP CODE----
因此，您已经向浏览器发送了内容，无法发送标题（会话启动，Cookie，重定向等）;删除那些行。
在您的配置脚本中，您使用的是 $ connect 变量，因此您必须在登录脚本中使用它而不是 $ link