致命错误：require_once（）：无法打开required'\php'；（包括路径='；B:\xamp\php\pear'；）

致命错误：require_once（）：无法打开所需的'.\DbConnect.php' （包括_path='B:\xamp\php\pear'）在 第12行的B:\xamp\htdocs\Library\includes\DbOperations.php

---

'？'
这是一个用文本
？
而不是参数的字符串。请阅读：此错误的确切原因是什么？回显此
目录名（_文件）。'/DbConnect.php'
并验证文件路径是否正确
<?php
include'B:\xamp\php\pear';
class DbOperations{
private $con;
function __construct(){
     require_once dirname(_FILE_).'/DbConnect.php'; -->Error
     $db = new DbConnect();
     $this->con = $db->connect();
 }
 /*CRUD -> C -> CREATE*/
/*********************STUDENT TABLE******************************/
function createstudent($username,$password,$email){
    $password = md5($pass);
    $stmt = $this->con->prepare("INSERT INTO `tbl_student` (`id`, `username`, `email`, `password`, `CourseName`, `Semester`, `RegDate`, `updationDate`) VALUES (NULL, '?', '?', '?', '?', '?', current_timestamp(), NULL);");
    $stmt->bind_param("sss",$username,$password,$email);
    /*$stmt->bind_param(':username',$username,PDO::PARAM_STR);
    $stmt->bind_param(':password',$password,PDO::PARAM_STR);
    $stmt->bind_param(':email',$email,PDO::PARAM_STR);*/
    if($stmt->excute()){
        return true;
    }
    else {
        return false;
    }
}
?>

<?php 
//include('B:\xamp\php\pear');
class DbConnect{
    private $con;
    function __construct(){
    }
    function connect(){
        include_once dirname(_FILE_).'/Constants.php';
        $this->con = new mysqli(DB_HOST,DB_USER,DB_PASS,DB_NAME);
        if(mysqli_connect_errno()){
            echo "Failed to connect with Database".mysqli_connect_err();
        }
        return $this->con;
    }
}
?>