VB.Net/File Directory/Binary File Write

Creating a random file

<source lang="vbnet"> Imports System.IO Imports System.Collections Imports System.Windows.Forms Imports System.Runtime.Serialization.Formatters.Binary Imports System.Runtime.Serialization Public Class MainClass

  Public Shared Sub Main()
     Const NUMBER_OF_RECORDS As Integer = 100
     " record for writing to disk
     Dim blankRecord As Employee = New Employee("f","l")
     Dim fileOutput As FileStream
     Dim binaryOutput As BinaryWriter
     Dim fileName As String = "test.dat"
     Dim i As Integer
        Try
           fileOutput = New FileStream(fileName,FileMode.Create, FileAccess.Write)
           fileOutput.SetLength(Employee.SIZE * NUMBER_OF_RECORDS)
           binaryOutput = New BinaryWriter(fileOutput)
           For i = 0 To NUMBER_OF_RECORDS - 1
              fileOutput.Position = i * Employee.SIZE
              binaryOutput.Write(blankRecord.firstName)
              binaryOutput.Write(blankRecord.lastName)
           Next
           Console.WriteLine("File Created")
        Catch fileException As IOException
           Console.WriteLine("Cannot write to file")
        End Try

     " close FileStream
     If (fileOutput Is Nothing) <> False Then
        fileOutput.Close()
     End If
     " close BinaryWriter
     If (binaryOutput Is Nothing) <> False Then
        binaryOutput.Close()
     End If
  End Sub

End Class <Serializable()> Public Class Employee

  Public firstName, lastName As String
  Shared Public SIZE As Integer = 200 
  Public Sub New(ByVal first As String, ByVal last As String)
     firstName = first
     lastName = last
  End Sub 
  Public Overrides Function ToString() As String
     Return firstName & " " & lastName
  End Function 

End Class

      </source>

Save Structure to a Binary File

<source lang="vbnet"> Imports System Imports System.IO Imports System.Windows.Forms Public Class MainClass

  Shared Sub Main()
       Dim emp As New Employee
       Dim file_num As Integer = FreeFile()
       FileOpen(file_num, "MYFILE.DAT", OpenMode.Random, _
            OpenAccess.ReadWrite, OpenShare.Shared, _
            Len(emp))
       FilePut(file_num, New Employee(1, "A", "A"))
       FilePut(file_num, New Employee(2, "B", "B"))
       FilePut(file_num, New Employee(3, "C", "C"))
       FilePut(file_num, New Employee(4, "D", "D"))
       FilePut(file_num, New Employee(5, "E", "E"))
       FilePut(file_num, New Employee(6, "F", "F"))

       " Close the file.
       FileClose(file_num)
  End Sub 

End Class

   Public Structure Employee
       Public ID As Integer
       <VBFixedString(15)> Public FirstName As String
       <VBFixedString(15)> Public LastName As String
       Public Sub New(ByVal new_id As Integer, ByVal first_name As String, _
        ByVal last_name As String)
           ID = new_id
           FirstName = first_name
           LastName = last_name
       End Sub
       Public Overrides Function ToString() As String
           Return ID & ": " & FirstName & " " & LastName
       End Function
   End Structure
          
      </source>

Use BinaryWriter to store information into a binary file

<source lang="vbnet"> Imports System Imports System.IO Public Class MainClass

 Shared Sub Main()
   Dim aFileStream As FileStream
   Try
     aFileStream = New FileStream("test.txt", FileMode.OpenOrCreate,FileAccess.Write)
     Dim myBinaryWriter As New BinaryWriter(aFileStream)
     myBinaryWriter.Write("Hello world")
     myBinaryWriter.Write(1)
   Catch e As Exception
     Console.WriteLine(e.StackTrace)
   Finally
     If Not (aFileStream Is Nothing) Then aFileStream.Close()
   End Try
 End Sub
 

End Class

      </source>