File field not getting updated-Collection of common programming errors

i tried to update file cck field of a content type as below from another node as below.

file gets uploaded but results error in updating file field .

localhost
Error
The website encountered an unexpected error. Please try again later.
Error message

    Notice: Undefined index: fid in file_field_presave() (line 219 of C:\xampp\htdocs\drupal\modules\file\file.field.inc).
    Warning: array_flip(): Can only flip STRING and INTEGER values! in DrupalDefaultEntityController->load() (line 173 of C:\xampp\htdocs\drupal\includes\entity.inc).
    Notice: Trying to get property of non-object in file_field_presave() (line 220 of C:\xampp\htdocs\drupal\modules\file\file.field.inc).
    Warning: Creating default object from empty value in file_field_presave() (line 221 of C:\xampp\htdocs\drupal\modules\file\file.field.inc).
    Notice: Undefined property: stdClass::$uri in file_save() (line 601 of C:\xampp\htdocs\drupal\includes\file.inc).
    Notice: Undefined index: fid in file_field_update() (line 261 of C:\xampp\htdocs\drupal\modules\file\file.field.inc).
    Notice: Undefined index: fid in file_field_update() (line 287 of C:\xampp\htdocs\drupal\modules\file\file.field.inc).
    Notice: Undefined property: stdClass::$fid in file_usage_add() (line 685 of C:\xampp\htdocs\drupal\includes\file.inc).
    PDOException: SQLSTATE[23000]: Integrity constraint violation: 1048 Column 'fid' cannot be null: INSERT INTO {file_usage} (fid, module, type, id, count) VALUES (:db_insert_placeholder_0, :db_insert_placeholder_1, :db_insert_placeholder_2, :db_insert_placeholder_3, :db_insert_placeholder_4); Array ( [:db_insert_placeholder_0] => [:db_insert_placeholder_1] => file [:db_insert_placeholder_2] => node [:db_insert_placeholder_3] => 32 [:db_insert_placeholder_4] => 1 ) in file_usage_add() (line 692 of C:\xampp\htdocs\drupal\includes\file.inc).

I guess you should use this way:

$file = file_save_data($image, 'public://' . $filename, FILE_EXISTS_RENAME);
$node->field_ftest[LANGUAGE_NONE][0]=(array)$file;

You should use Form API to create and manage file uploads and their management. You can do something like this instead:

...
$form['file'] = array(
    '#title' => t('File'),
    '#type' => 'managed_file',
    '#description' => t('File formats: %format. Maximum: %max_size. Resolution %resolution', array('%format' => 'Jpg, Jpeg, Png, Gif', '%max_size' => '800 Kb', '%resolution' => '80x100')),
    '#upload_location' => 'public://',
);
...

and submit function:

...
$node = node_load(32);
$file_d = $form_state['values']['file'];
$file = file_load($file_d);
$file->status = FILE_STATUS_PERMANENT;
file_save($file);
file_usage_add($file, 'node', 'TYPE', $file->fid);
$file_info = image_get_info($file->uri);

$file_arr = array(
  'fid' => $file->fid,
  'alt' => '',
  'title' => '',
  'width' => $file_info['width'],
  'height' => $file_info['height'],
  'uid' => $file->uid,
  'filename' => $file->filename,
  'uri' => $file->uri,
  'filemime' => $file->filemime,
  'filesize' => $file->filesize,
  'status' => 1,
  'timestamp' => $file->timestamp,
  'rdf_mapping' => array(),
);

$node->field_ftest[LANGUAGE_NONE][0] = $file_arr;
node_save($node);
...