1. Introduction
2. File Access
3. The Basics
4. Strings
5. More Strings
6. Practical Uses

Comments

1. chenneke
   21 Jun 2007 at 14:43

   it helps me a lot, thanks

2. Ali Matthew
   28 Jun 2006 at 10:57

   Thanks it was very helpfull

3. Sampat Sharma
   01 May 2006 at 07:34

   I want to read a binary file whitch saved by a Grid Option.how Can i Read this file and retrieve data from file. 

4. Mohit Sharma
   12 May 2004 at 08:03

   I am struggling for long time to display a GIF file on an ASP page. I have tried to return a GIF file in  few formats
   from a webservice.
   Webservice returns the images as MemoryStream.GetBuffer(). Its an array of unsigned bytes.I also tried to return it
   in base64 encoded format.
   

   
   I can call this webservice in either of 2 ways
   

   
   1) Directly from ASP -- It returns me this ..
   

   
   ÿØÿàJFIF
   
   
   `ÿÛC    $.' ",#(7),01444'9=82<.342ÿÛC
 2!!22222222222222222222222222222222222222222222222222ÿÀ((
"

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}
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!1 <br> AQaq"2B‘¡±Á #3RðbrÑ $4á%ñ&'()*56789:CDEFGHIJSTUVWXYZcdefghijstuvwxyz‚ƒ„…†‡ˆ‰Š’“”•–—˜™š¢£¤¥¦§¨©ª²³´µ¶·¸¹ºÂÃÄÅÆÇÈÉÊÒÓÔÕÖ×ØÙÚâãäåæçèéêòóôõö÷øùúÿÚ 
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   2) From VB(again I am returning byte array) which inturn is called by ASP -- I get the
   same junk as above.
   

   
   I need to convert it as a GIF file in my ASP page.
   Can you guys suggest how it could by achived. I am open to change code at any layer.
   

   
   Note - I am not getting any file back from VB or Web service. I am only getting it in some encoded format(byte array
   or base64)
   

   
   My ASP code is like this -
   

   
   <%@ LANGUAGE="VBSCRIPT"%>
   <% Response.Expires = 0
   Response.Buffer = True
   Response.clear
   Response.contenttype =  "image/gif"
   Response.AddHeader "content-disposition", "inline; filename=MyMap.gif"
   

   
   Set myEXE = CreateObject("ExFireSafeMapInfoTool.MapInfo")
   varGetImage = myEXE.GenerateMapForHousehold()
   RESPONSE.BinaryWrite (varGetImage)
   

   
   'Value of varGetImage -- Dont know what format is this?
   

   
   ÿØÿàJFIF
   
   
   `ÿÛC    $.' ",#(7),01444'9=82<.342ÿÛC
 2!!22222222222222222222222222222222222222222222222222ÿÀ((
"

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}
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   %>
   

   
   My VB Component function is something like this -
   

   
   Public Function GenerateMapForHousehold() As Variant
   

   
    Dim szFileName      As String
    Dim oSOAP           As New SoapClient30     'Soap Type Library 3
    Dim bytImage()      As Byte
    Dim szPicture       As String
    Dim iCount          As Integer
    Dim File            As Integer
    File = FreeFile
    
      'Make the Call to Web Service to retrive the Image.
      oSOAP.ClientProperty("ServerHTTPRequest") = True
      oSOAP.MSSoapInit "http://localhost/WebService1/GetImage.asmx?WSDL"
      bytImage = oSOAP.GetImage("bayshore.gif")
      GenerateMapForHousehold3A = bytImage
      
      'I can retreive this image in VB using this code -
      'szPicture = App.Path & "\Test.gif"
      'Open szPicture For Binary As File
      'For iCount = LBound(bytImage) To UBound(bytImage) - 1
      '  Put #1, , bytImage(iCount)
      'Next
      'Close #1
      'GenerateMapForHousehold = szPicture
      'Set Form1.imgTest.Picture = LoadPicture(GenerateMapForHousehold)
   

   
   End function
   

   
   

   
   And web service(c#) method is something like this-
   

   
   using System.IO;
   using System.Drawing.Imaging;
   public byte[] GetImage(string strFileName)
          {
              StreamWriter sr;
              Byte sIn = new Byte();
              Image MyImage;
              MemoryStream MemStr = new MemoryStream();
              MyImage = new Bitmap(Server.MapPath( strFileName));
              MyImage.Save(MemStr, ImageFormat.Jpeg);
              return  MemStr.GetBuffer();
          //I have 1 more function to return base64 encoded string but dont know how to use it further.
   

   
      }
   

   
   Please help.
   Thanks
   Mohit
   e mail - mohitFL@hotmail.com
   

5. MathiasRav
   03 Mar 2004 at 13:15
   Well I didn't notice the date in the upper left corner
6. Sonic D Hedgehog
   02 Mar 2004 at 14:22
   Well this thread's ancient, I know that now. Heck, I think I knew back then too, but didn't bother typing it out.
7. MathiasRav
   02 Mar 2004 at 10:41
   Never use 1 as file number. Use
   Code:

   
   Dim FileNo As Integer
   FileNo = FreeFile
   Open ... ... As #FileNo
   Get #FileNo, , FileStr
   

   
   [courier new]// Mathias[/courier new]
8. MathiasRav
   02 Mar 2004 at 10:38

   Hi. I'm having a similar problem, I just can't get the header. I want to check if a .BMP file is in the right format. The header is BM, but i'm just getting M8 as header. That must be wrong . How do you get the header? Isn't it just

   Code:

   Get #FileNo, 2, sHeader

   ??

9. davour
   04 Nov 2003 at 13:34
   I am having a trouble reading binary data
   
   I have the following from the tutorial:
   
   Quote:

   
   Dim nFileNum As Integer, sString As String
   nFileNum = FreeFile
   Open "C:\Example\Example.txt" For Binary Access _
     Read Lock Read Write As #nFileNum
   sString = Space$(6)
   Get #nFileNum, 1, sString
   Close #nFileNum
   MsgBox sString
   [/Quote]
   
   It reads the value in the file fine, but since i wrote the file in binary it reads it back in binary and all i get is a ""
   
   Am i missing something... does the file need to be read in a certain way?
10. Rob Williams
    31 Aug 2003 at 22:19

    I don't know what I am doing wrong, but I would like to be able to read and write to *.exe and *.dll files. The problem is that it only gets the header ( MZ ). Does anyone know what I may have done wrong, or another method that can open EXE and DLL files? Thanks!
    

    
    -vivi0

11. Sonic D Hedgehog
    30 Mar 2003 at 01:49

    How do I find the size of the file?
    [edit] Nevermind. LOF(1) seems to be it.

12. Sonic D Hedgehog
    30 Mar 2003 at 01:43

    If everything you ever wanted to work with were an INI file, that'd be perfect. But if you want to make any sort of editor chances are you'll be using Binary file access.

13. David Gerstman
    26 Dec 2002 at 12:30

    Hi Shotgunner,
    I assumed that a binary file that could be read by C/C++ could also be read in VB.  There are constraints on how to do that but here goes.  In the code I posted before I created a binary file.  Here's the code I used to read it and write out the equivalent integer (or more correctly long) data in VB:
    Private Sub cmdRead_Click()
       Dim ibyte(2) As String * 1
       Dim tot, temp As Long
       Dim ind As Integer
       For ind = 0 To 19
           Get #1, , ibyte(1)
           Get #1, , ibyte(2)
           temp = Asc(ibyte(2)) * 2 ^ 8
           tot = Asc(ibyte(1)) + temp
           txtData(ind * 3).Text = tot
           txtData((ind * 3) + 1).Text = Asc(ibyte(1))
           txtData((ind * 3) + 2).Text = Asc(ibyte(2))
       Next ind
    End Sub
    

    
    Private Sub mnuExitProgram_Click()
       Unload frmBin
    End Sub
    

    
    Private Sub mnuFileOpen_Click()
       Open "test.dat" For Binary As #1
       cmdRead.Enabled = True
    End Sub
    

    
    Obviously I won't be sending you the forms.
    Here's the C (or more correctly the VC++ ) code that accomplishes a similar purpose:
    

    
    

    include <fstream.h>

    
    

    include <iomanip.h>

    
    int main()
    {
       unsigned ind, tot;
       unsigned char byte[2];
       ifstream infile("test.dat", ios::in );
    

    
       for ( ind = 1; ind <= 20; ind++ )
       {
           infile.read( byte, 2 );
           tot = byte[0] + ( byte[1] << 8 );
           cout << setw(8) << ind << setw(8) << tot << setw(8) << (int)byte[0] << setw(8) << (int)byte[1] << endl;
       }
       return 0;
    }
    

    
    Both programs read in the binary data from test.dat and displayed (either to console or to form) the equivalent numerical data.

14. John Smith
    20 Dec 2002 at 17:55
    thanx
15. David Gerstman
    20 Dec 2002 at 08:35
    Quote:

    [1]Posted by TheShotGunnner on 24 Nov 2002 09:16 PM[/1]
    Is it possible to read a C++ written binary file into visual basic and write it again using vb then have it read by c++. If it is then can someone please tell me. also how do you write a typefef structure into a file using c++. Does anyone know. I would really appreciate it.
    

    
    
    A binary file is a binary file regardless of which language creates it.  The following code reads in a binary file 2 bytes at a time (the read statement) and then writes them to another binary file 2 bytes at a time (the write statement)
    #include <fstream.h>
    #include <iomanip.h>
    int main()
    {
       int ind, tot;
       unsigned char byte[2];
       ifstream infile("2000_09_28_18_40_11_Sen2_Grp0.dat", ios::in );
       ofstream outfile("test.dat", ios::binary );
    
       for ( ind = 1; ind <= 20; ind++ )
       {
           infile.read( byte, 2 );
           outfile.write( byte, 2 );
           tot = byte[0] + ( byte[1] << 8 );
           cout << setw(8) << ind << setw(8) << tot << setw(8) << (int)byte[0] << setw(8) << (int)byte[1] << endl;
       }
       return 0;
    }
    
    I plan to test test.dat later and make sure that VB can read it.  But I have little doubt that it will.  You may wonder what I was writing to the screen with cout.  (This is important to consider.)    Often binary files contain 2 byte integers split into two separate bytes.  Here I was taking the bytes and recombining them into their original value. For example the first two number that are read are 208(byte[0] ) and 7 (byte[1]).  Shifting the the 1 byte 7 8 places (the equivalent of multiplying by 256) and then adding it to byte[0] to make an integer 2 bytes long equals 2000.  7 * 256 + 208 = 1792 + 208 = 2000 or looked at another way 00000111 010110000 is a 16 bit representation of 2000.
    
    I hope this helps.
    
    David
16. John Smith
    24 Nov 2002 at 21:16
    Is it possible to read a C++ written binary file into visual basic and write it again using vb then have it read by c++. If it is then can someone please tell me. also how do you write a typefef structure into a file using c++. Does anyone know. I would really appreciate it.
17. Osnr
    01 Nov 2002 at 23:09

    And don't forget, data files shouldn't be written to the registry.

18. Net Gert
    11 Dec 2001 at 14:03

    The Len() function returns null if the file is open in binary mode. Use the LOF() function instead.
    

    
    Another thing, String() function is better to use than Space() function because if you have used value bigger than new value, Space() only fills string with spaces, leaving the size as is, but String() resizes the strng.
    

19. gigsvoo
    24 Oct 2001 at 06:40

    This is a 2 ways method, if your program very much independent on settings inside the INI files you just have to read and write the INI files at all times.
    

    
    Or if ur program is mostly put the value inside the registry for a one-time settings of something in conjunction to the system setting, registry would be better.
    

    
    But i prefer using INI files since it can be separated from the syste, registry and avoid corruption.
    

    
    One more thing is in registry, you can organize ur setting in parent and child relationship but not INI file.
    

20. Jamie Lindgren
    23 Oct 2001 at 23:28

    Since you can do the same kind of stuff like this and save it to the registry, which is easier, why use binary files?  I could see it if you had a LOT of values, but then wouldn't you just use and INI file or something for conveienience?  I guess keeping things secret, like passwords, you might use a bin file for, but what could it be used for other than that?

21. Developer Fusion Bot
    01 Jan 1999 at 00:00

    This thread is for discussions of Binary Files.