How to assign value from one file field to another programmatically?
I have done it. Here is the code that I used to solved the problem.

  $file = file_load($fid);
  $user-&gt;field_user_file = array(
    'und' =&gt; array(
      '0' =&gt; array(
        'fid' =&gt; $file-&gt;fid,
        'filename' =&gt; $file-&gt;filename,
        'filemime' =&gt; $file-&gt;filemime,
        'uri' =&gt; $file-&gt;uri,
        'status' =&gt; 1,
        'display' =&gt; 1
      )
    )
  );