修复方法：警告：mysqli_stmt_close（）期望参数1为mysqli_stmt，布尔值在

Question

我正在尝试制作收件箱系统，并且在编写撰写文件时，出现标题中出现的错误。

我已经读过一个问题，将其放在不同的花括号中是行不通的。

请通过向我发送正确的代码来帮助我。 会很感激的 谢谢！

<?php
// Include config file
require_once "../html/incl/php/db/config.php";

// Define variables and initialize with empty values
$recipient = $subject = $message = "";
$recipient_err = $subject_err = $message_err = "";

// Processing form data when form is submitted
if($_SERVER["REQUEST_METHOD"] == "POST"){
    // Validate recipient
    $input_recipient = trim($_POST["recipient"]);
    if(empty($input_recipient)){
        $recipient_err = "Please enter a recipient.";
    } elseif(!filter_var($input_recipient, FILTER_VALIDATE_REGEXP, array("options"=>array("regexp"=>"/^[a-zA-Z\s]+$/")))){
        $recipient_err = "Please enter a valid recipient.";
    } else{
        $recipient = $input_recipient;
    }

    // Validate subject
    $input_subject = trim($_POST["subject"]);
    if(empty($input_subject)){
        $subject_err = "Please enter a subject.";
    } else{
        $subject = $input_subject;
    }

    // Validate message
    $input_message = trim($_POST["message"]);
    if(empty($input_message)){
        $message_err = "Please enter a message.";
    } else{
        $message = $input_message;
    }

    // Check input errors before inserting in database
    if(empty($recipient_err) && empty($subject_err) && empty($message_err)){
        // Prepare an insert statement
        $sql = "INSERT INTO messages (recipient, subject, message) VALUES (?, ?, ?)";

        if($stmt = mysqli_prepare($link, $sql)){
            // Bind variables to the prepared statement as parameters
            mysqli_stmt_bind_param($stmt, "sss", $param_recipient, $param_subject, $param_message);

            // Set parameters
            $param_recipient = $recipient;
            $param_subject = $subject;
            $param_message = $message;

            // Attempt to execute the prepared statement
            if(mysqli_stmt_execute($stmt)){
                // Records created successfully. Redirect to landing page
                header("location: index.php");
                exit();
            } else{
                echo "Something went wrong. Please try again later.";
            }

        }

        mysqli_stmt_close($stmt);
    }

    // Close connection
    mysqli_close($link);
}
?>

警告：mysqli_stmt_close（）期望参数1为mysqli_stmt，布尔值在

中给出