Reading a file into a byte array

Question

User1635080783 posted

I need to read a base64 string into a byte array, with the intention of converting it from base64 to binary and writing it back out as a jpeg. (Because that's what it is-- a base-64 encoded jpeg image)

The following is what I have so far:

             Dim fpath As String = Server.MapPath("myfile.txt")
 
            Dim fs As System.IO.FileStream
            fs = File.Open(fpath, FileMode.Open, FileAccess.Read, FileShare.None)
            Dim filelen As Long = fs.Length
            Dim buffer As Byte()

            Try
                fs.Read(buffer, 0, filelen)
            Catch ex As Exception
                Trace.Write("ERROR", " Error: " & ex.Message)
            End Try

            fs.Read(buffer, 0, filelen)

 

When I compile it I get a  warning:  Variable 'buffer' is used before it has been assigned a value. A null reference exception could result at runtime.

And this is the error message I get when I run it:

Buffer cannot be null.
Parameter name: array

 So how do I initialize "buffer"?  Or is there a better way to do this?

Thanks very much.

 

 

 

Answer 1

User-1657381277 posted

You are missing this. Dim buff(fs.Length) As Byte. Also keep in mind if the file size is big, (500 MB or greater you may want to read it in in chunks.  Also put a try catch around it in case things hang.

 

            Dim fpath As String = Server.MapPath("myfile.txt")

            If fi.Exists AndAlso fileName.Length > 0 Then
                  Dim fs As System.IO.FileStream = System.IO.File.Open(fpath, IO.FileMode.Open, IO.FileAccess.Read)
                  Dim buff(fs.Length) As Byte
                  If fs.Length > 0 Then
                        fs.Read(buff, 0, fs.Length - 1)
                        fs.Close()
                        buff = Nothing
                        fs = Nothing
                  Else
                        'Empty File
                  End If

            End If

  

Answer 2

User1635080783 posted

 Thanks very much for your help!!

Answer 3

User-266950512 posted

Dim buff(fs.Length) As Byte

should be

Dim buff(fs.Length-1) As Byte