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POSimple File I/O in Visual Basic 2013
 

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  1. POSimple File I/O in Visual Basic 2013
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    <p>I want to learn how to write and read data from files using Visual Basic Studio Express 2013 for Windows Desktop.</p> <p>Specifically, I have a class called Pilots. The class includes text of a first and last name, and integers representing rank, skill, missions and status.</p> <p>There is an ArrayList called Squadron that contains 18 (at start) Pilots. </p> <p>What I want to do is save and then load all the data in Squadron to a file. And I'm not sure how to get it to work properly. I've read numerous books and sites, but somewhere along the line, I'm just not comprehending how to get it to work correctly.</p> <p>At this point, I've been able to write the data to a file.... but I'm having no luck getting it back out of the file.</p> <p>To write it out... I'm using this code:</p> <pre><code> Dim currentpilot As New Pilot("John", "Doe") ' Create the BinaryWriter and use File.Open to create the file. Using writer As BinaryWriter = New BinaryWriter(File.Open("squadron.dat", FileMode.Create)) ' Write each integer. writer.Write(SquadronList.Count) For index = 0 To SquadronList.Count - 1 currentpilot = CType(SquadronList(index), Pilot) writer.Write(currentpilot.pFirstName) writer.Write(currentpilot.pLastName) writer.Write(currentpilot.pSkill) writer.Write(currentpilot.pRank) writer.Write(currentpilot.pStatus) writer.Write(currentpilot.pMissions) writer.Write(currentpilot.pKills) Next End Using </code></pre> <p>The <code>writer.Write(SquadronList.Count)</code> line is there to record the number of actual Pilot records in the file. I don't know if that's necessary or not.</p> <p>The file does write to disk and just looking at it with notepad, it does seem to have the correct data.</p> <p>The problem is getting it back out. This code fails quickly...</p> <pre><code> Using reader As BinaryReader = New BinaryReader(File.OpenRead("squadron.dat")) Dim index As Integer = reader.ReadInt32 For counter = 0 To index - 1 currentpilot.pFirstName = reader.ReadString currentpilot.pLastName = reader.ReadString currentpilot.pSkill = reader.ReadInt16 currentpilot.pRank = reader.ReadInt16 currentpilot.pStatus = reader.ReadInt16 currentpilot.pMissions = reader.ReadInt16 currentpilot.pKills = reader.ReadInt16 SquadronList.Add(currentpilot) Next End Using </code></pre> <p>So... any suggestions or guidance will be appreciated!</p>
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    1. USMPelletier
    1. USCodexofRome
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      1. POSimple File I/O in Visual Basic 2013
      1. USCodexofRome
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    1. COHave you tried using System.IO.streamreader instead of binaryreader?
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      1. POSimple File I/O in Visual Basic 2013
      1. USGavin Perkins
    2. COHow about xml serialization? Then you can save and read these files into your class object.
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      1. POSimple File I/O in Visual Basic 2013
      1. USOneFineDay
    3. COReadInt16() is pretty unlikely to work correctly, it almost surely wasn't written with the BinaryWriter.Write(Int16) overload. You'd have to use CShort() explicitly in the Write() call to ensure it is a match. Or use the correct Read version that matches the property type. There are certainly better ways to do this, using binary or XML serialization.
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      1. POSimple File I/O in Visual Basic 2013
      1. USHans Passant
 

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