PHPで複数のfileをupload

HTML側
<form method="POST" enctype="multipart/form-data" action="merge.php">
<input type="file" name="upload_file[]" multiple id="file">
<input type="submit" name="submit" value="upload" />

PHP側
<?php
if(count($_FILES['upload_file'])) {
    foreach($_FILES['upload_file'] as $file) {
        print_r($file);
    }
}

参考：https://davidwalsh.name/multiple-file-upload