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POUsing StreamReader and StreamWriter to Modify Files
 

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    <p>I am trying to use StreamReader and StreamWriter to Open a text file (fixed width) and to modify a few specific columns of data. I have dates with the following format that are going to be converted to packed COMP-3 fields. </p> <pre><code>020100718F 020100716F 020100717F 020100718F 020100719F </code></pre> <p>I want to be able to read in the dates form a file using StreamReader, then convert them to packed fields (5 characters), and then output them using StreamWriter. However, I haven't found a way to use StreamWriter to right to a specific position, and beginning to wonder if is possible.</p> <p>I have the following code snip-it.</p> <pre><code>System.IO.StreamWriter writer; this.fileName = @"C:\Test9.txt"; reader = new System.IO.StreamReader(System.IO.File.OpenRead(this.fileName)); currentLine = reader.ReadLine(); currentLine = currentLine.Substring(30, 10); //Substring Containing the Date reader.Close(); ... // Convert currentLine to Packed Field ... writer = new System.IO.StreamWriter(System.IO.File.Open(this.fileName, System.IO.FileMode.Open)); writer.Write(currentLine); </code></pre> <p>Currently what I have does the following:</p> <pre><code>After: !@#$%0718F 020100716F 020100717F 020100718F 020100719F !@#$% = Ascii Characters SO can't display </code></pre> <p>Any ideas? Thanks!</p> <p><strong>UPDATE</strong> Information on Packed Fields COMP-3</p> <p>Packed Fields are used by COBOL systems to reduce the number of bytes a field requires in files. Please see the following SO post for more information: <a href="https://stackoverflow.com/questions/8974091/sql-how-to-get-comp-3-packed-decimal">Here</a></p> <p>Here is Picture of the following date "20120123" packed in COMP-3. This is my end result and I have included because I wasn't sure if it would effect possible answers.</p> <p><img src="https://i.stack.imgur.com/If9Gn.png" alt="Picture of the following date 20120123 packed"></p> <p>My question is how do you get StreamWriter to dynamically replace data inside a file and change the lengths of rows?</p>
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    1. COI can't seem to locate what your actual question is. It might help if you explain what a packed COMP-3 data field is. Might also help if you tell us the expected results.
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      1. USSecurity Hound
    2. COPlease don't prefix your titles with "C#" and such. That's what tags are for.
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      1. USJohn Saunders
    3. COAfter BCD encoding you'll get **binary** data. Don't use StreamWriter to write it to file, use FileStream instead.
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