riceman0
asked on
Reading a binary file with VB.NET
Let's try this again, a little more concisely:
I am trying to convert some code from VB6.0 to VB.NET, this particular loop populates a data structure from a binary file, and I am having a huge problem getting equivalent results. I'll cut and paste the old code and new code below, and if anyone can tell me what I'm doing wrong, or (even better!) give me a couple of snippets, I'd be eternally graceful!
The problems are in the GetVariable function of the second section. Just pasted the rest for completeness. Part of the problem this isn't simple is because the BinaryReader doesn't seem to support random access... but I'm not married to it.
Thanks!
**************************
old, working VB6.0 code
**************************
Private Type XVDataType
sText As String * 50
iNumPoints As Integer
dData(50) As Double
End Type
Private Sub ButtonGo_Click()
Dim X as XVDataType
Dim f as String
f = "C:\Documents and Settings\crice\My Documents\Active Tasks\TCFLO\Project\TCFLO\
X = GetVariable(f, 4) ' calls the getvariable function with some dummy data, to test
End Sub
Private Function GetVariable(sRestartFile As String, iNumXVar As Integer) As XVDataType
' inumvar is 1-based
Dim XV As XVDataType
' get the variable definitions
Dim ind As Long
Open sRestartFile For Binary As #1
ind = 254 ' header offset
Get #1, ind + (iNumXVar - 1) * 508 + 1, XV.iNumPoints
Dim n As Integer
For n = 0 To XV.iNumPoints - 1
Get #1, ind + (iNumXVar - 1) * 508 + 9 + n * 8, XV.dData(n)
Next n
Get #1, ind + (iNumXVar - 1) * 508 + 459, XV.sText
GetRestartExternalVariable
' close the file and exit
ext:
Close #1
Exit Function
End Function
**************************
new, mostly not working VB.NET code
**************************
Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
Call GetVariable( _
"C:\Documents and Settings\crice\My Documents\Active Tasks\TCFLO\Project\TCFLO\
, 4)
End Sub
Private Function GetVariable(ByVal sRestartFile As String, ByVal iNumXVar As Integer) As XVDataType
Dim XV As New XVDataType
' get the variable definitions
Dim ind As Long = 254 ' header offset
If System.IO.File.Exists(sRes
Dim binReader As New System.IO.BinaryReader(Fil
binReader.ReadBytes(ind + (iNumXVar - 1) * 508)
XV.iNumPoints = binReader.ReadByte() ' <---- THIS WORKS, gets the right number of points
For n As Integer = 0 To XV.iNumPoints - 1
XV.dData(n) = binReader.ReadSingle ' <---- this doesn't work worth a darn
'XV.dData(n) = binReader.ReadDouble ' <------ this didn't work either
'binReader.ReadBytes(8) ' < ------ nor this
'Get #1, ind + (iNumXVar - 1) * 508 + 9 + n * 8, XV.dData(n) ' <------- the equivalent VB6.0 code
Next n
XV.sText = binReader.ReadChars(10) ' <------ doesn't work
binReader.Close()
End If
End Function
I am trying to convert some code from VB6.0 to VB.NET, this particular loop populates a data structure from a binary file, and I am having a huge problem getting equivalent results. I'll cut and paste the old code and new code below, and if anyone can tell me what I'm doing wrong, or (even better!) give me a couple of snippets, I'd be eternally graceful!
The problems are in the GetVariable function of the second section. Just pasted the rest for completeness. Part of the problem this isn't simple is because the BinaryReader doesn't seem to support random access... but I'm not married to it.
Thanks!
**************************
old, working VB6.0 code
**************************
Private Type XVDataType
sText As String * 50
iNumPoints As Integer
dData(50) As Double
End Type
Private Sub ButtonGo_Click()
Dim X as XVDataType
Dim f as String
f = "C:\Documents and Settings\crice\My Documents\Active Tasks\TCFLO\Project\TCFLO\
X = GetVariable(f, 4) ' calls the getvariable function with some dummy data, to test
End Sub
Private Function GetVariable(sRestartFile As String, iNumXVar As Integer) As XVDataType
' inumvar is 1-based
Dim XV As XVDataType
' get the variable definitions
Dim ind As Long
Open sRestartFile For Binary As #1
ind = 254 ' header offset
Get #1, ind + (iNumXVar - 1) * 508 + 1, XV.iNumPoints
Dim n As Integer
For n = 0 To XV.iNumPoints - 1
Get #1, ind + (iNumXVar - 1) * 508 + 9 + n * 8, XV.dData(n)
Next n
Get #1, ind + (iNumXVar - 1) * 508 + 459, XV.sText
GetRestartExternalVariable
' close the file and exit
ext:
Close #1
Exit Function
End Function
**************************
new, mostly not working VB.NET code
**************************
Private Sub Button4_Click(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles Button4.Click
Call GetVariable( _
"C:\Documents and Settings\crice\My Documents\Active Tasks\TCFLO\Project\TCFLO\
, 4)
End Sub
Private Function GetVariable(ByVal sRestartFile As String, ByVal iNumXVar As Integer) As XVDataType
Dim XV As New XVDataType
' get the variable definitions
Dim ind As Long = 254 ' header offset
If System.IO.File.Exists(sRes
Dim binReader As New System.IO.BinaryReader(Fil
binReader.ReadBytes(ind + (iNumXVar - 1) * 508)
XV.iNumPoints = binReader.ReadByte() ' <---- THIS WORKS, gets the right number of points
For n As Integer = 0 To XV.iNumPoints - 1
XV.dData(n) = binReader.ReadSingle ' <---- this doesn't work worth a darn
'XV.dData(n) = binReader.ReadDouble ' <------ this didn't work either
'binReader.ReadBytes(8) ' < ------ nor this
'Get #1, ind + (iNumXVar - 1) * 508 + 9 + n * 8, XV.dData(n) ' <------- the equivalent VB6.0 code
Next n
XV.sText = binReader.ReadChars(10) ' <------ doesn't work
binReader.Close()
End If
End Function
ASKER CERTIFIED SOLUTION
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>>
What you have read is the first 4 BITS of the data ...
<<
should be
>>
What you have read is the first BYTE of the data ...
<<
Roger
What you have read is the first 4 BITS of the data ...
<<
should be
>>
What you have read is the first BYTE of the data ...
<<
Roger
Roger brings up a good point about the size of Ints being different in VB.Net.
Important questions:
Are you reading the OLD file created by VB6?
...or are you attempting to read a NEW file that was created by VB.Net code with new .Net types (and consequently new different sizes)?
Have you considered using XML or possibly Binary Serialization instead of Structures?
Important questions:
Are you reading the OLD file created by VB6?
...or are you attempting to read a NEW file that was created by VB.Net code with new .Net types (and consequently new different sizes)?
Have you considered using XML or possibly Binary Serialization instead of Structures?
ASKER
To answer the questions:
* no error messages, just wrong values
* correct, the data in the file is not ordered like the order of the structure -- maybe a little misleading; it is # points, data, text
* the VB.NET class is reading the exact same file as the VB6.0 class, they were both produced by the same ancient DOS program that this is post-processing :)
I will try the suggestions in the next couple of hours, thanks!
Does the binReader.Position change after the readByte..?
Does the ReadByte work instead of the ReadSingle at the first problem.?