How to read from a binary file using VBScript
<p>I'm very new to VBScript, correct me at any point, if I'm wrong.</p>

<p>I'm facing issue while reading from a binary file.</p>

<p>My need is to read the last four bytes from a binary file and compare the same with a local variable.</p>

<p>But the issue is I'm getting value of <code>0x3F</code> while converting the ASCII characters (of last 4 bytes) to Hex equivalent. But I'm able to see valid data in the files created by this script by opening, where the same binary stream is used to write to file.</p>

<p>I'm not sure if I'm missing something</p>

<p>Below is the code for reference</p>

<pre><code>Const adTypeBinary = 1 
Const adSaveCreateOverWrite = 2 
Const CRC = 4
Dim BinaryStream, OutStream, StartPos, Bytes
'debug
Dim fso, MyFile
Const ForReading = 1, ForWriting = 2, ForAppending = 8
Const TristateUseDefault = -2, TristateTrue = -1, TristateFalse = 0
'debug
Dim bootstrapIOPCRC, bootIOPCRC, appIOPCRC, bootDSPCRC, codeDSPCRC, dataDSPCRC
Dim a(1)
bootstrapIOP = "C:\Bins\1.bin"
bootIOP = "C:\Bins\2.bin"
appIOP = "C:\Bins\3.bin"
bootDSP = "C:\Bins\4.bin"
codeDSP = "C:\Bins\5.bin"
dataDSP = "C:\Bins\6.bin"
'Create the BinaryStream object 
Set BinaryStream = CreateObject("ADODB.Stream") 
'Set it up and load in the source file 
BinaryStream.Type = adTypeBinary 
BinaryStream.Open 
' *** For bootstrapIOP
Bytes = 0
StartPos = 0
BinaryStream.LoadFromFile bootstrapIOP
'Create OutStream 
Set OutStream = CreateObject("ADODB.Stream") 
OutStream.Type = adTypeBinary 
OutStream.Open 
SET objFSO = CREATEOBJECT("Scripting.FileSystemObject")
SET objFile = objFSO.GetFile(bootstrapIOP)
Bytes = CLng(objFile.Size)
StartPos = Bytes-CRC
'selecting the required data
BinaryStream.Position = StartPos 
BinaryStream.CopyTo OutStream, CRC
OutStream.SaveToFile "C:\bootstrapIOP.txt", adSaveCreateOverWrite 
bootstrapIOPCRC = 0
bootstrapIOPCRC = OutStream.Read ( CRC)
strHex =""
MsgBox((Asc(Mid(bootstrapIOPCRC,1,1))))
MsgBox(Mid(bootstrapIOPCRC,2,1))
MsgBox(bootstrapIOPCRC)
For i=1 To Len(bootstrapIOPCRC)
    strHex = strHex + Hex(Asc(Mid(bootstrapIOPCRC,i,1)))
Next
If (strHex = "") Then 
    MsgBox "Yippy"
Else 
    MsgBox(strHex)
End If
MsgBox(Len(bootstrapIOPCRC))
Set objFSO1=CreateObject("Scripting.FileSystemObject")
' How to write file
outFile="c:\test.txt"
Set objFile = objFSO1.CreateTextFile(outFile,True)
objFile.Write a(0)
objFile.Write a(1)
objFile.Close
' *** For bootIOP
Bytes = 0
StartPos = 0
BinaryStream.LoadFromFile bootIOP
SET objFile = objFSO.GetFile(bootIOP)
Bytes = CLng(objFile.Size)
StartPos = Bytes-CRC
'selecting the required data
BinaryStream.Position = StartPos 
BinaryStream.CopyTo OutStream, CRC
OutStream.SaveToFile "C:\bootIOP.txt", adSaveCreateOverWrite 
bootIOPCRC = 0
bootIOPCRC = OutStream.Read ( CRC)
' *** For appIOP
Bytes = 0
StartPos = 0
BinaryStream.LoadFromFile appIOP
SET objFile = objFSO.GetFile(appIOP)
Bytes = CLng(objFile.Size)
StartPos = Bytes-CRC
'selecting the required data
BinaryStream.Position = StartPos 
BinaryStream.CopyTo OutStream, CRC
OutStream.SaveToFile "C:\appIOP.txt", adSaveCreateOverWrite 
appIOPCRC = 0
appIOPCRC = OutStream.Read ( CRC)
' *** For bootDSP
Bytes = 0
StartPos = 0
BinaryStream.LoadFromFile bootDSP
SET objFile = objFSO.GetFile(bootDSP)
Bytes = CLng(objFile.Size)
StartPos = Bytes-CRC
'selecting the required data
BinaryStream.Position = StartPos 
BinaryStream.CopyTo OutStream, CRC
OutStream.SaveToFile "C:\bootDSP.txt", adSaveCreateOverWrite 
bootDSPCRC = 0
bootDSPCRC = OutStream.Read ( CRC)
' *** For codeDSP
Bytes = 0
StartPos = 0
BinaryStream.LoadFromFile codeDSP
SET objFile = objFSO.GetFile(codeDSP)
Bytes = CLng(objFile.Size)
StartPos = Bytes-CRC
'selecting the required data
BinaryStream.Position = StartPos 
BinaryStream.CopyTo OutStream, CRC
OutStream.SaveToFile "C:\codeDSP.txt", adSaveCreateOverWrite 
codeDSPCRC = 0
codeDSPCRC = OutStream.Read ( CRC)
' *** For dataDSP
Bytes = 0
StartPos = 0
BinaryStream.LoadFromFile dataDSP
SET objFile = objFSO.GetFile(dataDSP)
Bytes = CLng(objFile.Size)
StartPos = Bytes-CRC
'selecting the required data
BinaryStream.Position = StartPos 
BinaryStream.CopyTo OutStream, CRC
OutStream.SaveToFile "C:\dataDSP.txt", adSaveCreateOverWrite 
dataDSPCRC = 0
dataDSPCRC = OutStream.Read ( CRC)
</code></pre>