尝试获取属性时出现问题'；行数'；非对象输入和未定义变量的类型：Php中的stmt_结果

当我试图在登录数据库时检查数据库中的用户和密码时，我遇到了一个问题 答复错误消息：

注意：尝试在第27行的/Applications/XAMPP/xamppfiles/htdocs/studyact/login.php中获取非对象的属性'num_row' 用户名或密码不正确，请检查并重试

我输入的用户和密码正确

php文件：

<?php

//html 
  $user_staff = $_POST["user_staff"];
  $pass_staff = $_POST["pass_staff"];


// Create connection



$servername = "localhost";
$username = "root";
$password = "";
$db ="studyact";

$con = new mysqli($servername, $username, $password,$db);

// Check connection
if ($con->connect_error) {
  die("Connection failed: " . $con->connect_error);
}else{
   $stmt =$con-> prepare("select * from loginstaff where user_staff = ?");
  $stmt->bind_param("s",$user_staff);
  $stmt->execute();
  $stmtresult = $stmt->get_result();
   if($stmtresult-> num_row > 0){
      $data = $stmtresult-> fetch_assoc();
       if($data["pass_staff"] === $pass_staff){
          echo "<h2>Login Successfully</h2>";
    }
    else{
          echo "<h2> Sorry User name or Password is incorrect.</h2>";
      }
  
    }else{
        echo "<h2> User name or Password is incorrect, please check and try again.</h2>";
    }
   }
?>

---

第27行有一个打字错误
如果（$stmtresult->num_rows>0）

---

mysqli\u stmt:：$num\u rows-返回从服务器获取的行数

$stmtresult

未

$stmt\u result

。已更新，但仍然有效