Pdf file not working

<?php if ( ! defined('BASEPATH')) exit('No direct script access allowed');

require_once dirname(__FILE__) . '/tcpdf/tcpdf.php';

class Pdf extends TCPDF
{
    function __construct()
    {
        parent::__construct();
    }
}

A PHP Error was encountered
Severity: Warning

Message: require_once(C:\xampp\htdocs\OnlineExaminationCI\application\libraries/tcpdf/tcpdf.php): failed to open stream: No such file or directory

Filename: libraries/Pdf.php

Line Number: 3

Backtrace:

File: C:\xampp\htdocs\OnlineExaminationCI\application\libraries\Pdf.php
Line: 3
Function: _error_handler

File: C:\xampp\htdocs\OnlineExaminationCI\application\libraries\Pdf.php
Line: 3
Function: require_once

File: C:\xampp\htdocs\OnlineExaminationCI\application\controllers\Hasilujian.php
Line: 73
Function: library

File: C:\xampp\htdocs\OnlineExaminationCI\index.php
Line: 315
Function: require_once


Fatal error: require_once(): Failed opening required 'C:\xampp\htdocs\OnlineExaminationCI\application\libraries/tcpdf/tcpdf.php' (include_path='C:\xampp\php\PEAR') in C:\xampp\htdocs\OnlineExaminationCI\application\libraries\Pdf.php on line 3
A PHP Error was encountered
Severity: Compile Error

Message: require_once(): Failed opening required 'C:\xampp\htdocs\OnlineExaminationCI\application\libraries/tcpdf/tcpdf.php' (include_path='C:\xampp\php\PEAR')

Filename: libraries/Pdf.php

Line Number: 3

Backtrace: