Subject: Re: Visual Basic Binary file access Answered By: theta-ga on 02 Nov 2002 09:14 PST Rated:

Reading binary data in VB is really quite easy. I'm am providing some
example code here, with pointers to articles you might refer to in
case you want more examples or explainations.
Here, I will try to read a record ExampleData from a binary file.
Since you say that you already know the binary file record structure,
you can substitute my ExampleData structure with your own record
structure.
I have included code for both VB 6 & VB 7.NET
Explaination of code snippets : I try to read/write a fixed length
record from/to a binary file.The record contains a fixed length string
of 10 chars and an integer value. I first write one record of this
type to the file and then read one record from the file in binary
mode.I also show you how to get the length of an open file in VB.

CODE SNIPPETS FOR VB5/VB6
--------------------------
  'Define ExampleData structure
  Type Exampledata
        Name as String * 10  'This is a fixed length string of 10
characters
        Age as Integer
  End Type
  Dim myData As ExampleData  ' Declare variable of type ExampleData

  ...

  'Open Binary File
  'FOr Binary Access, The Open function has the following format :
  'Open filename For Binary As filenumber
   Open "c:\BinaryFile.bin" For Binary As #1
  
  'When writing to a binary file, we use the Put statement.
  'Put #FileNumber, ByteNumber, VariableName
  'ByteNumber is the file pos from which we start writing the data
  Put #1,,myData  ' Writes mydata in file at the current position

  'Close the file
  Close #1
 
....

  'Read data from the file
  Open "c:\BinaryFile.bin" For Binary As #1
  'To read data, use the Get function
  'Get #FileNumber, ByteNumber, VariableName
  'Data is read from the binary file position specified by ByteNumber
  Get #1,,myData 'Read in data from the current file pos
  'Print Data
  Debug.Print myData.Name
  Debug.Print myData.Age
  'To get the length of file, use the LOF(filenumber) function
  Debug.Print "Length of the Binary File = " & LOF(1)
  'Close File
  Close #1

 RELATED LINKS
 -------------
  - Binary Files - File Access by James Crowley
    A very good tutorial On using Binary Files under VB. Highly
recommended!
    ( http://www.developerfusion.com/show/85/1/ )
  - MSDN Help topic: "Using Binary File Access"
    The standard MS Help Article on Binary files in VB 6
    ( http://msdn.microsoft.com/library/devprods/vs6/vbasic/vbcon98/vbconusingbinaryfileaccess.htm
)
  - MS KnowledgeBase Q257794 - HOWTO: Use Binary File Access with
Visual Basic
    Adds to the above MSDN Article. Provides example code for
variable length records access in a binary file using VB.
    ( http://support.microsoft.com/default.aspx?scid=KB;EN-US;Q257794&
)
  - MS Support : File Access with Visual Basic® for Applications
    Although for VBA, the same code works for VB6. Provides a list of
all the functions that can be used with the Binary file Access mode in
VB.Also provides example code.
    ( http://support.microsoft.com/default.aspx?scid=/support/excel/content/fileio/fileio.asp
)
======================

CODE SNIPPETS FOR VB7.NET
-------------------------
  'Define ExampleData structure
  Structure Exampledata
      Name as String 'Fixed length string of 10
characters
        Age as Integer
  End Type
  Public myData As ExampleData  ' Declare variable of type
ExampleData
 
  ...

  'Open Binary File
  'For Binary Access, use the FileOpen function which has the form :
  'FileOpen(FileNumber, FileName, OpenMode.Binary)
   FileOpen (1,"c:\BinaryFile.bin", OpenMode.Binary
  
  'When writing to a binary file, we use the FilePut() function.
  'FilePut( FileNumber,VariableName)
  FilePut(1,myData)  ' Writes mydata in file at the current position

  'Close the file
  FileClose(1)
 
....

  'Read data from the file
  FileOpen (1,"c:\BinaryFile.bin", OpenMode.Binary
  'To read data, use the FileGet function
  'FileGet (FileNumber, VariableName)
  FileGet(1,myData) 'Read in data from the current file pos
  'Display length of open file using the func. LOF(filenumber)
  Debug.WriteLine(LOF(1))
  'Close File
  FileClose(1)

RELATED LINKS
-------------
- MSDN VB.NEt File Functions Reference
    - FileOpen()
      ( http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vblr7/html/vastmopen.asp
)
    - FilePut()
      ( http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vblr7/html/vastmput.asp
)
    - FileGet()
      ( http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vblr7/html/vafctget.asp)
    - LOF()
      ( http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vblr7/html/vafctlof.asp
)

MSDN Article : Binary File Access
( http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vbcn7/html/vaconopeningfileforbinaryaccess.asp
)

===========================
I hope the above answer will satisfy your needs.
If you need any clarifications, just ask.
Till the, Happy Coding !
:)