in my VB.net Application id like to overwrite and add new content of a text file
What Code do I need to use?
Thanks
Read (ie: load) everything in the TXT file into your program.
Dim sFullPathToFile As String = Application.StartupPath & "\Sample.txt"
Dim sAllText As String = ""
Using xStreamReader As StreamReader = New StreamReader(sFullPathToFile)
sAllText = xStreamReader.ReadToEnd
End Using
Dim arNames As String() = Split(sAllText, vbCrLf)
'Just for fun, display the found entries in a ListBox
For iNum As Integer = 0 To UBound(arNames)
If arNames(iNum) > "" Then lstPeople.Items.Add(arNames(iNum))
Next iNum
Because you wanted to overwrite everything in the file, we now use StreamWriter (not a StreamReader like before).
'Use the True to indicate it is to be appended to existing file
'Or use False to open the file in Overwrite mode
Dim xStreamWRITER As StreamWriter = New StreamWriter(sFullPathToFile, False)
'Use the carriage return character or else each entry is on the same line
xStreamWRITER.Write("I have overwritten everything!" & vbCrLf)
xStreamWRITER.Close()
Related
I have this code
Dim fileReader As System.IO.StreamReader
fileReader =
My.Computer.FileSystem.OpenTextFileReader("Filepath")
Dim stringReader As String
'read csv file from first to last line
While fileReader.ReadLine <> ""
'get data of line
stringReader = fileReader.ReadLine()
'check the number of commas in the line
Dim meh As String() = stringReader.Split(",")
If meh.Length > 14 Then
My.Computer.FileSystem.WriteAllText("Filepath", "asd", True)
ElseIf meh.Length < 14 Then
My.Computer.FileSystem.WriteAllText("Filepath", "asd", True)
ElseIf meh.Length = 14 Then
MsgBox("This line of the file has " & stringReader & meh.Length & "commas")
End If
End While
End
End Sub
To explain, the above code would check EACH line of a CSV file to check weather the contents has 14 commas('). Then if that line has more commas, the code will reduce it to 14, and if not, it would write commas so that it would be equal to 14. The above conditions are not created yet, so the code is just for testing. I read something about WriteAllText and this code gives me the error :
The process cannot access the file 'filepath' because it is being used by another process.
Which, I think, means that I cant edit the CSV file because I'm currently using its data.
My question is, how could I edit the contents of the CSV file even when I am checking its contents?
Please do disregard this code
My.Computer.FileSystem.WriteAllText("Filepath", "asd", True)
as I use this code just for testing, if ever I could manage to write it to the CSV file.
I Thank you for all your help.
If your CSV is not too big, you can read it in memory and work with it. When you have finish you can write it again on disk.
'Declare 2 List (or you can work directly with one)
Dim ListLines As New List(Of String)
Dim ListLinesNEW As New List(Of String)
'Read the file
Using MyCSVread As New IO.FileStream("C:\MyCSV.csv", IO.FileMode.Open, IO.FileAccess.ReadWrite)
'Read all the lines and put it in a list of T (string)
Using sReader As IO.StreamReader = New IO.StreamReader(MyCSVread)
Do While sReader.Peek >= 0
ListLines.Add(sReader.ReadLine)
Loop
End Using
End Using
'Your code for work with the line. Here you can write the new lines in the NEW list of string or work directly in the first
For L As Integer = 0 To ListLines.Count - 1
Dim meh As String() = ListLines(L).Split(",")
If meh.Length > 14 Then
'your code ...
ElseIf meh.Length < 14 Then
'your code ...
ElseIf meh.Length = 14 Then
MessageBox.Show("The line " & (ListLines(L) + 1) & " of the file has " & meh.Length & "commas", "MyApp", MessageBoxButtons.OK, MessageBoxIcon.Exclamation)
End If
Next
'Open again the file for write
Using MyCSVwrite As New IO.FileStream("C:\MyCSV.csv", IO.FileMode.Open, IO.FileAccess.ReadWrite)
'Write back the file with the new lines
Using sWriter As IO.StreamWriter = New IO.StreamWriter(MyCSVwrite)
For Each sLine In ListLinesNEW.ToArray
sWriter.WriteLine(sLine)
Next
End Using
End Using
The "Using" auto close the filestream or a streamreader/write or what you use. Then you will not have problem like "file already in use".
Hope this help.
FIRST PROBLEM:
I am looking for an easiest way to read multiple text files at one time and extract all the duplicate lines from each text file and copy those duplicate lines to a new text file with headings representing name of parent text file. I am dealing with more than 20 text files at a time and it is a mess to go through each one by one. Secondly, I am dealing with large / heavy file (more or less 30,000 lines in each file) .. I am currently using a program with "Stream Reader" and "Stream Writer" and I prefer to have the same approach for my understanding. OR any new and easy way is Welcome !!
SECOND PROBLEM:
I want to compare 2 text files and get the duplicate lines on to a new text file. I don't want to remove/delete/overwrite: Just to copy them across to a new text file.
Please use openfiledialog and savefiledialog for the files.
Thanks a lot in advance.
Best Regards
VB_Learner
Dim Dim optxtfile As New OpenFileDialog
optxtfile.RestoreDirectory = True
optxtfile.Multiselect = False
optxtfile.Filter = "txt files (*.txt)|*.txt"
optxtfile.FilterIndex = 1
optxtfile.ShowDialog()
If (Not optxtfile.FileName = Nothing) Then
Dim lines As New List(Of String)
Using sr As New System.IO.StreamReader(optxtfile.FileName)
While sr.Peek <> -1
Dim line As String = sr.ReadLine()
Dim isNew As Boolean = True
For Each dupl As String In lines
If (dupl = line) Then isNew = False
Next
If (isNew) Then lines.Add(sr.ReadLine())
End While
End Using
Dim svDir As String
If (My.Computer.FileSystem.FileExists(optxtfile.FileName)) Then
My.Computer.FileSystem.DeleteFile(optxtfile.FileName)
svDir = optxtfile.filename
Dim svtxtfile As New SaveFileDialog
svtxtfile.RestoreDirectory = True
svtxtfile.Filter = "txt files (*.txt)|*.txt"
svtxtfile.FilterIndex = 1
svtxtfile.ShowDialog()
If (svtxtfile.FileName = Nothing) Then
svDir = optxtfile.FileName
Else
svDir = svtxtfile.FileName
End If
End If
Using write2text As New System.IO.StreamWriter(svDir)
For Each line As String In lines
write2text.WriteLine(line)
Next
End Using
End If
End Sub
I've been trying to make a program that is able to create a file with a .key extension, which contains a 5 line text.
It is fundamental to have 5 lines, otherwise it won't work.
I use
Dim filepath As String = TextBox1.Text + "\\rarreg.key"
Dim rarreg As New IO.StreamWriter(filepath, True)
rarreg.Write(String.Join(Environment.NewLine, hiddenTxt))
The hiddenTxt contains all the text needed and it's multilined.
However, when I click on the button to call this functions, it succesfully creates the file, but it comes empty.
Try this
' Add any initialization after the InitializeComponent() call.
Dim filepath As String = ""
Dim dialog As New SaveFileDialog
dialog.DefaultExt = "key"
dialog.FileName = "rarreg.key"
dialog.InitialDirectory = "c:\temp"
Dim results As DialogResult = dialog.ShowDialog()
If results <> Windows.Forms.DialogResult.Cancel Then
filepath = dialog.FileName
End If​
I need to create several text files in vb.net based on values entered in a spreadsheet. Each text file will be named 'valuename.txt'.
I populate an array with the value names as they are entered:
issues(j) = Grid1.Cells(1, j).Value
Now I need to open text files with their names. I would like to do something along the lines of:
Dim Filename As String = "C:\" & Grid1.Cells(1, j).Value & ".txt"
Dim issues(j) As New System.IO.StreamWriter(Filename)
When I enter this in Visual Studio, it says it does not like:
issues(j)
Do I have any other options?
It seems like the code you have posted is inside a for loop with j being the counting variable.
You are already building a filename from the cell values, so just declare the streamwriter as a new variable and use it:
For j = 0 To Grid1.Rows.Count - 1 'Assumed by me
'Create the filename for the current row
Dim Filename As String = "C:\" & Grid1.Cells(1, j).Value & ".txt"
'The Using block makes sure that the ressources used by the streamwriter are disposed again.
'It is equivalent as Dim sw As New IO.Streamwriter, but Using should be preferred
Using sw As New IO.StreamWriter(Filename)
'Use the streamwriter to write the data
End Using
'If you additionally want to store the values in an array for whatever reason
issues(j) = Grid1.Cells(1, j).Value
Next
Your Dim issues(j) statement does not make any sense.
To append data to an existing file, use the overload of the StreamWriter constructor:
Using sw As New IO.StreamWriter(Filename, True)
The second parameter defines if data should be added to the file.
You can use Using to declare a new StreamWriter:
Dim Filename As String = "C:\" & Grid1.Cells(1, j).Value & ".txt"
Using fsw As New System.IO.StreamWriter(Filename)
'Do Something
End Using
But if you insist to use a list of StreamWriter (I don't know why) then you can do something like this:
Dim fsw As New List(Of System.IO.StreamWriter)
fsw(j) = New System.IO.StreamWriter(Filename)
'Do Something
fsw(j).Close
fsw(j).Dispose
Helo there!
it seems that i am facing a problem with my code in VB.net. Please be patient as i am a complete beginner in programming. I am trying to code a program that will load 2 or more txt files, find and exclude specific lines (starting with some characters or contain some characters) and then merge and save only one file that will contain all the information after the editing (from all the files).
I am using openfiledialog and i have set the multiselect to true. Below is the code for the OpenfileDialog:
If OpenFileDialog1.ShowDialog = Windows.Forms.DialogResult.OK Then
For Each File In OpenFileDialog1.FileNames
My.Computer.FileSystem.ReadAllText(OpenFileDialog1.FileName)
Next
If i am correct, it loads the filenames and reads all the text from the files. For the editing i am using the following code:
Dim outputLines As New List(Of String)()
For Each line As String In System.IO.File.ReadLines(OpenFileDialog1.FileName)
Uline1 = line.StartsWith("text1")
Uline2 = line.StartsWith("text2")
Uline3 = line.StartsWith("text3")
Uline4 = line.StartsWith("text4")
Uline5 = line.StartsWith("text5")
Uline6 = line.StartsWith("text7")
Uline7 = line.StartsWith("sometext")
Trash = line.Contains("^")
If Uline1 Or Uline2 Or Uline3 Or Uline4 Or Uline5 Or Uline6 Or Uline7 Or Trash Then
outputLines.Remove(line)
Else
outputLines.Add(line)
End If
Next
For the output i am using a savefiledialog with the following code:
SaveFileDialog1.DefaultExt = "txt"
SaveFileDialog1.Filter = "txt files (*.txt)|*.txt|All files (*.*)|*.*"
SaveFileDialog1.RestoreDirectory = True
If (SaveFileDialog1.ShowDialog() = DialogResult.OK) Then
System.IO.File.WriteAllLines(SaveFileDialog1.FileName, outputLines)
Although the files are being loaded correctly, the edit seems to happen only in one file (the last selected) and again the program saves only one file.
Could you please point me to the right direction?
You need to nest your loops through the file names returned by the open file dialog, and the lines returned by the ReadLines calls. You also don't need to remove lines from the outputLines list, since they are never added. Something like:
If OpenFileDialog1.ShowDialog = Windows.Forms.DialogResult.OK Then
Dim outputLines As New List(Of String)()
For Each fileName In OpenFileDialog1.FileNames
For Each line As String In System.IO.File.ReadLines(fileName)
Uline1 = line.StartsWith("text1")
Uline2 = line.StartsWith("text2")
Uline3 = line.StartsWith("text3")
Uline4 = line.StartsWith("text4")
Uline5 = line.StartsWith("text5")
Uline6 = line.StartsWith("text7")
Uline7 = line.StartsWith("sometext")
Trash = line.Contains("^")
If Not (Uline1 Or Uline2 Or Uline3 Or Uline4 Or Uline5 Or Uline6 Or Uline7 Or Trash) Then
outputLines.Add(line)
End If
Next
Next
End If
If the files are very large you will start to run into memory issues, and will need to write the data out as it is read instead of keeping it all in memory.
UPDATE
Based on the comments, if you want to check the following line to determine if the current line should be written, you could use something like this. Note the use of ReadAllLines and the For loop.
Dim outputLines As New List(Of String)()
For Each fileName In OpenFileDialog1.FileNames
Dim lines() As String = System.IO.File.ReadAllLines(fileName)
For i As Integer = 0 To lines.Count - 1
Dim line As String = lines(i)
If line.StartsWith("19") AndAlso i < lines.Count - 2 AndAlso lines(i + 1).StartsWith("15") Then
outputLines.Add(line)
outputLines.Add(lines(i + 1))
i += 1
End If
Next
Next