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VB.NET Discussion Thread
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Feb 22nd, 2009

How to check if a file is empty

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Ok, I know about how to check for the end of a file, but what I need to know, is if you create a new file, thats empty, how do you check if it really is empty, and if its the same as EOF, then what am I doing wrong with this code here:

VB.NET Syntax (Toggle Plain Text)
 
        If Dir(My.Application.Info.DirectoryPath & "\TurbineData.xml") <> "" Then
 
            If (TextBox1.Text.Equals("") Or TextBox2.Text.Equals("") Or TextBox3.Text.Equals("") Or TextBox4.Text.Equals("")) Then
 
                Dim title2 = "Invalid Values"
                MsgBox(" Form contains no values to save.", , title2)
 
            Else
                Dim ExistingData As New MyDatum
 
                Dim Serializer As New System.Xml.Serialization.XmlSerializer(GetType(MyDatum))
 
                If (File.Exists(My.Application.Info.DirectoryPath & "\TurbineData.xml" & Not EOF(1))) Then                     
 
                    Dim OpenStream As System.IO.FileStream = System.IO.File.Open(My.Application.Info.DirectoryPath & "\TurbineData.xml", IO.FileMode.Open)
 
                    ExistingData = Serializer.Deserialize(OpenStream)
 
                    OpenStream.Close()
                Else
                    Dim err05 = "File does not Exist"
                    MsgBox("Creating new XML file.", , err05)
 
                End If
 
                Dim NewData As New MyData
 
                TextBox1.Focus()
                NewData.DateStamp = CDate(Date.Today()) 'DateValue(Now)
                NewData.TimeStamp = CDate(TimeString())
                NewData.Gap = gaptext.Text
 
                ExistingData.Add(NewData)
 
                Dim SaveStream As System.IO.FileStream = System.IO.File.Open(My.Application.Info.DirectoryPath & "\TurbineData.xml", IO.FileMode.Create)
 
                Serializer.Serialize(SaveStream, ExistingData)
 
                SaveStream.Close()
 
                Dim title3 = "Save Alert"
                MsgBox("Data Saved to " & My.Application.Info.DirectoryPath & " \TurbineData.xml", , title3)
 
            End If
 
        Else
            Dim err05 = "File does not Exist"
            MsgBox("Creating new XML file.", , err05)
 
           Dim SaveStream As System.IO.FileStream = System.IO.File.Open(My.Application.Info.DirectoryPath & "\TurbineData.xml", IO.FileMode.Create)
            SaveStream.Close()
        End If
        If Dir(My.Application.Info.DirectoryPath & "\TurbineData.xml") <> "" Then

            If (TextBox1.Text.Equals("") Or TextBox2.Text.Equals("") Or TextBox3.Text.Equals("") Or TextBox4.Text.Equals("")) Then

                Dim title2 = "Invalid Values"
                MsgBox(" Form contains no values to save.", , title2)

            Else
                Dim ExistingData As New MyDatum

                Dim Serializer As New System.Xml.Serialization.XmlSerializer(GetType(MyDatum))

                If (File.Exists(My.Application.Info.DirectoryPath & "\TurbineData.xml" & Not EOF(1))) Then                     

                    Dim OpenStream As System.IO.FileStream = System.IO.File.Open(My.Application.Info.DirectoryPath & "\TurbineData.xml", IO.FileMode.Open)

                    ExistingData = Serializer.Deserialize(OpenStream)

                    OpenStream.Close()
                Else
                    Dim err05 = "File does not Exist"
                    MsgBox("Creating new XML file.", , err05)

                End If

                Dim NewData As New MyData

                TextBox1.Focus()
                NewData.DateStamp = CDate(Date.Today()) 'DateValue(Now)
                NewData.TimeStamp = CDate(TimeString())
                NewData.Gap = gaptext.Text
               
                ExistingData.Add(NewData)

                Dim SaveStream As System.IO.FileStream = System.IO.File.Open(My.Application.Info.DirectoryPath & "\TurbineData.xml", IO.FileMode.Create)

                Serializer.Serialize(SaveStream, ExistingData)

                SaveStream.Close()

                Dim title3 = "Save Alert"
                MsgBox("Data Saved to " & My.Application.Info.DirectoryPath & " \TurbineData.xml", , title3)

            End If

        Else
            Dim err05 = "File does not Exist"
            MsgBox("Creating new XML file.", , err05)

           Dim SaveStream As System.IO.FileStream = System.IO.File.Open(My.Application.Info.DirectoryPath & "\TurbineData.xml", IO.FileMode.Create)
            SaveStream.Close()
        End If

Thats my code there, and the idea of this is that if the file is empty, then create a new entry in the xml, if the file already has data in it, then add to the file, dont overwrite the data.

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Tamir09

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since Feb 2009

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Feb 22nd, 2009

Re: How to check if a file is empty

Ah.... You are posting VB.NET code in the VB 4/5/6 Forum.

Comatose

Team Colleague

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Taboo Programmer

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since Dec 2004

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Feb 23rd, 2009

Re: How to check if a file is empty

Oh I didnt know there was a difference...thought it was the same forum. I wonder if anyone has a solution to this?

Tamir09

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Feb 23rd, 2009

Re: How to check if a file is empty

VB.NET Syntax (Toggle Plain Text)
Private Sub RenameFile(ByRef fileNameFull As String)
    Dim fileI As FileInfo = New FileInfo(fileNameFull)
    If fileI.Exists Then
        Dim binReader As New BinaryReader(File.Open(fileNameFull, FileMode.Open))
        Dim fileClosed As Boolean = False
        Try
            ' read the first 4 bytes into a buffer to 
            ' determine if the file is empty.
            Dim testArray As Byte() = {0, 0, 0, 0}
            Dim count As Integer = binReader.Read(testArray, 0, 3)
            If count <> 0 Then 'file NOT empty
                ' Reset the position in the stream to zero.
                binReader.BaseStream.Seek(0, SeekOrigin.Begin)
                'do append stuff
            Else
                'file empty
            End If
        Catch ex As Exception
            If Not fileClosed Then
                binReader.Close()
                fileClosed = True
            End If
            MsgBox("Uncaught general Exception error. " + ex.GetType().Name + vbNewLine + ex.Message)
        Finally
            If Not fileClosed Then
                binReader.Close()
                fileClosed = True
            End If
        End Try
    End If
End Sub
Private Sub RenameFile(ByRef fileNameFull As String)
    Dim fileI As FileInfo = New FileInfo(fileNameFull)
    If fileI.Exists Then
        Dim binReader As New BinaryReader(File.Open(fileNameFull, FileMode.Open))
        Dim fileClosed As Boolean = False
        Try
            ' read the first 4 bytes into a buffer to 
            ' determine if the file is empty.
            Dim testArray As Byte() = {0, 0, 0, 0}
            Dim count As Integer = binReader.Read(testArray, 0, 3)
            If count <> 0 Then 'file NOT empty
                ' Reset the position in the stream to zero.
                binReader.BaseStream.Seek(0, SeekOrigin.Begin)
                'do append stuff
            Else
                'file empty
            End If
        Catch ex As Exception
            If Not fileClosed Then
                binReader.Close()
                fileClosed = True
            End If
            MsgBox("Uncaught general Exception error. " + ex.GetType().Name + vbNewLine + ex.Message)
        Finally
            If Not fileClosed Then
                binReader.Close()
                fileClosed = True
            End If
        End Try
    End If
End Sub

edgar5

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Feb 24th, 2009

Re: How to check if a file is empty

VB.NET Syntax (Toggle Plain Text)
Dim reader() As String
reader = File.ReadAllLines(spath)
length = reader.GetLength(0)
Dim reader() As String
reader = File.ReadAllLines(spath)
length = reader.GetLength(0)

If length=0 then your file is empty. I didn't checked this method with .xml, but with .txt it is working.

martonx

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This thread is solved

Either the thread starter or a moderator has marked this thread as solved. You can most likely trust the responses and answers given. There is most likely no reason for any further responses to be posted here. If you have a related question, please start a new thread in this forum instead.

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