title: Best Way to Load a File, Manipulate the Data, and Write a New File
body: <p>I have an issue where I need to load a fixed-length file.  Process some of the fields, generate a few others, and finally output a new file.  The difficult part is that the file is of part numbers and some of the products are superceded by other products (which can also be superceded).  What I need to do is follow the superceded trail to get information I need to replace some of the fields in the row I am looking at.  So how can I best handle about 200000 lines from a file and the need to move up and down within the given products?  I thought about using a collection to hold the data or a dataset, but I just don't think this is the right way.  Here is an example of what I am trying to do:</p>
  
  <pre><code>Before
  
  
  Part Number      List Price          Description                   Superceding Part Number        
   0913982                                                                        3852943        
   3852943            0006710            CARRIER,BEARING          
  
  After
  
  
  Part Number      List Price          Description                   Superceding Part Number      
   0913982            0006710            CARRIER,BEARING      3852943      
   3852943            0006710            CARRIER,BEARING   
  </code></pre>
  
  <p>As usual any help would be appreciated, thanks.</p>
  
  <p>Wade</p>