直到一两天前,这段代码才正常工作。我是php新手,正在学习php 5(完成课程后,我打算重新学习所有内容)我现在一直遇到的错误是:致命错误:无法在/home/claymati/public\u html/login中的write context中使用函数返回值。php第28行
<!doctype html>
<?php
ini_set( "display_errors", "on" );
error_reporting( E_ALL | E_STRICT );
ini_set( "include_path", "./includes" );
include( "dbinfo.inc" );
$cxn = mysqli_connect($host,$user,$passwd,$dbname)
or die ("couldn't connect to server");
?>
<?php
// Check if the user is already logged in, if yes then redirect him to welcome page
if(isset($_SESSION["loggedin"]) && $_SESSION["loggedin"] === true){
header("location: stored.inc");
exit;
}
// Define variables and initialize with empty values
$username = $password = "";
$username_err = $password_err = $login_err = "";
// Processing form data when form is submitted
if($_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
$sql = "SELECT id, username, password FROM users_login WHERE username = ?";
if($stmt = mysqli_prepare($cxn, $sql)){
// Bind variables to the prepared statement as parameters
mysqli_stmt_bind_param($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, $id, $username, $hashed_password);
if(mysqli_stmt_fetch($stmt)){
if(password_verify($password, $hashed_password)){
// Password is correct, so start a new session
session_start();
// Store data in session variables
$_SESSION["loggedin"] = true;
$_SESSION["id"] = $id;
$_SESSION["username"] = $username;
// Redirect user to welcome page
header("location: stored.inc");
} else{
// Password is not valid, display a generic error message
$login_err = "Invalid username or password.";
}
}
} else{
// Username doesn't exist, display a generic error message
$login_err = "Invalid username or password.";
}
} else{
echo "Oops! Something went wrong. Please try again later.";
}
// Close statement
mysqli_stmt_close($stmt);
}
}
// Close connection
mysqli_close($cxn);
}
?>
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>Login</title>
<link href="style.css" rel="stylesheet" type="text/css">
<style>
body{ font: 14px sans-serif; }
.wrapper{ width: 360px; padding: 20px; }
</style>
</head>
<body>
<div class="wrapper">
<h1>Login</h1><br>
<p>Please fill in your credentials to login.</p><br>
<?php
if(!empty($login_err)){
echo '<div class="alert alert-danger">' . $login_err . '</div>';
}
?>
<form action="<?php echo htmlspecialchars($_SERVER["PHP_SELF"]); ?>" method="post">
<div class="form-group">
<label>Username</label>
<input type="text" name="username" class="form-control <?php echo (!empty($username_err)) ? 'is-invalid' : ''; ?>" value="<?php echo $username; ?>">
<span class="invalid-feedback"><?php echo $username_err; ?></span>
</div><br>
<div class="form-group">
<label>Password</label>
<input type="password" name="password" class="form-control <?php echo (!empty($password_err)) ? 'is-invalid' : ''; ?>">
<span class="invalid-feedback"><?php echo $password_err; ?></span>
</div>
<div class="form-group">
<input type="submit" class="btn btn-primary" value="Login">
</div>
<br>
<p>Don't have an account? Register Now </a>.</p>
</form>
</div>
</body>
</html>
代码的受影响部分:
<?php
// Check if the user is already logged in, if yes then redirect him to welcome page
if(isset($_SESSION["loggedin"]) && $_SESSION["loggedin"] === true){
header("location: stored.inc");
exit;
}
// Define variables and initialize with empty values
$username = $password = "";
$username_err = $password_err = $login_err = "";
// Processing form data when form is submitted
if($_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"]);
}
我不确定如何修复这个错误,因为我还是个新手。
