Solved

Downgrade FromBase64String from vb.net to vb6

Posted on 2010-09-02
4
1,305 Views
Last Modified: 2012-05-10
      I have a .Net example application that uses FromBase64String which I need to convert one function from and place in my legacy VB6 application, but I have been unable to find equivenent code.  The function accepts strdata as a string, decodes it from base64 and saves it as a bmp file.  Can anyone tell me how to accomplish this in VB6????

This is the whole code of the function.
       
    Private Sub SaveImageData(ByVal sigdata As String)

        Dim b() As Byte = Convert.FromBase64String(strdata)
        Dim fs As IO.FileStream = IO.File.Create("C:\temp.bmp")
        fs.Write(b, 0, b.Length)
        fs.Close()

0
Comment
Question by:FNDAdmin
4 Comments
 
LVL 17

Accepted Solution

by:
Zhaolai earned 500 total points
ID: 33588024
The following link should be helpful:

http://www.nonhostile.com/howto-encode-decode-base64-vb6.asp

0
 
LVL 12

Expert Comment

by:GMGenius
ID: 33588044
Here is a link to a sample class you could use
Use the DecodeToByteArray and save the byte array to file
http://www.mcmillan.org.nz/paradoxes/code/base64.html
I hope this helps
0
 
LVL 29

Expert Comment

by:nffvrxqgrcfqvvc
ID: 33588276
You can also use the cryptography API

Option Explicit
'egl1044
'WinXP or later
Private Const CRYPT_STRING_BASE64 As Long = &H1&

Private Declare Function CryptStringToBinaryW Lib "Crypt32.dll" ( _
  ByVal pszString As Long, _
  ByVal cchString As Long, _
  ByVal dwFlags As Long, _
  ByVal pbBinary As Long, _
  ByRef pcbBinary As Long, _
  ByVal pdwSkip As Long, _
  ByVal pdwFlags As Long) As Long

Public Function FromBase64String(ByVal data As String) As Byte()
  Dim Buffer() As Byte
  Dim dwBinaryBytes As Long
  dwBinaryBytes = LenB(data)
  ReDim Buffer(dwBinaryBytes - 1) As Byte
  If CryptStringToBinaryW(StrPtr(data), LenB(data), CRYPT_STRING_BASE64, _
    VarPtr(Buffer(0)), dwBinaryBytes, 0, 0) Then
    ReDim Preserve Buffer(dwBinaryBytes - 1) As Byte
    FromBase64String = Buffer
  End If
  Erase Buffer
End Function

Private Sub Form_Load()
  Dim image() As Byte
  image() = FromBase64String("c3VyZS4=") 'sure.
  Debug.Print StrConv(image, vbUnicode)
End Sub

Open in new window

0
 

Author Closing Comment

by:FNDAdmin
ID: 33596519
Thanks to everyone that posted solutions.  They all look like they shoudl work, but for some reason all three gave me a different decoded output, and only the XML was correct in my situation, I'm not exactly sure why.  Worked great though, thank you.
0

Featured Post

Master Your Team's Linux and Cloud Stack!

The average business loses $13.5M per year to ineffective training (per 1,000 employees). Keep ahead of the competition and combine in-person quality with online cost and flexibility by training with Linux Academy.

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

When designing a form there are several BorderStyles to choose from, all of which can be classified as either 'Fixed' or 'Sizable' and I'd guess that 'Fixed Single' or one of the other fixed types is the most popular choice. I assume it's the most p…
Enums (shorthand for ‘enumerations’) are not often used by programmers but they can be quite valuable when they are.  What are they? An Enum is just a type of variable like a string or an Integer, but in this case one that you create that contains…
Get people started with the process of using Access VBA to control Outlook using automation, Microsoft Access can control other applications. An example is the ability to programmatically talk to Microsoft Outlook. Using automation, an Access applic…
Get people started with the process of using Access VBA to control Excel using automation, Microsoft Access can control other applications. An example is the ability to programmatically talk to Excel. Using automation, an Access application can laun…

777 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question