php cURL 上传文件失败,是怎么回事？

curlPost.php

 <?php

    $post = array(
        'name' => 'wyjie',
        'img'  => '@D:/debug.exe'
        );

    //cURL发送post请求
    $ch = curl_init();
    curl_setopt($ch, CURLOPT_URL, 'http://localhost/demo/demo/curl/01.php');
    curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
    curl_setopt($ch, CURLOPT_POST, 1);
    curl_setopt($ch, CURLOPT_POSTFIELDS, $post);

    $optput = curl_exec($ch);
    curl_close($ch);

    echo $optput;

 ?>

01.php

 <?php
    print_r($_POST);
    print_r($_FILES);

 ?>

输出结果
Array ( [name] => wyjie [img] => @./debug.exe ) Array ( )