I'm using vb.net. Below is my code on read a txt file and my txt file is quite large. I successfully read and display my Test.txt in txt2.Text, I want my output inside the Test.txt same line by line to be display inside the txt2.Text, I have set up my txt2.Text as multiple line. So when i enlarge my txt2.Text, my output will be the same as inside the Test.txt file. how do i used VbCrLf inside my code?
Dim filename As String = "C:\Users\user\Documents\Test.txt"
Dim Line As String = ""
Dim sb As New StringBuilder
Using sr As StreamReader = File.OpenText(filename)
Line = sr.ReadLine
Do
If Line = "*" Then
Line = sr.ReadLine
Do
sb.Append(Line)
Line = sr.ReadLine
Loop Until Line = "**"
End If
Line = sr.ReadLine
Loop Until Line = ""
End Using
txt2.Text = sb.ToString
End Sub
Your loop remove the CarriageReturn and LineFeed characters from the input line.
You could readd them changing this line
sb.Append(Line)
to
sb.AppendLine(Line)
But you will find soon that you have a bigger problem.
Inside the loop you execute various ReadLine without checking if you have really another line available to read. I don't know the structure of your file, but some kind of error checking is advisable.
With a text file like this:
testdata10
*
testdata1
testdata2
testdata3
testdata4
testdata5
**
testdata11
Assuming that there are no more * before the ** is reached, this code will add the appropriate lines to the textbox as is:
Using sr As New IO.StreamReader("textfile1.dat")
Dim line As String = ""
While Not sr.EndOfStream
line = sr.ReadLine
If line = "*" Then
Do
TextBox1.AppendText(sr.ReadLine & vbNewLine)
Loop Until sr.Peek = Asc("*"c)
End If
End While
End Using
Related
Im trying to output the data from the second line of my textfile to a datagridview but when doing so it is also outputting every line after the the second line. This is what I have tried. Thanks
Dim lines = IO.File.ReadAllLines(OrderID & ".txt")
For index = 1 To lines.Length - 1
Dim cells = lines(index).Split(","c)
dgvOutput.Rows.Add(cells)
FileClose()
It's outputting every line after the second line, because that's what you're telling it to do when you iterate through the array of strings returns from ReadAllLines.
IO.File.ReadAllLines does not leave an output stream open. The file is closed. What it does do, is return a zero-based (by default) array of the contents of the file, with line breaks being the delimiter for the split.
To just get the contents of the second line, using ReadAllLines, this is what you need:
Dim lines = IO.File.ReadAllLines(OrderID & ".txt")
If lines.length >= 2 Then
Dim cells = lines(1).Split(","c)
dgvOutput.Rows.Add(cells)
End If
Now, that does have the overhead of reading the entire file in. If you open the file using a reader object, then you only need to read the first and second lines of the file to get that second line.
That would be something like this:
Dim reader as StreamReader = My.Computer.FileSystem.OpenTextFileReader(OrderId & ".txt")
Dim a as String
' This reads the first line, which we throw away
reader.ReadLine()
a = reader.ReadLine()
reader.Close()
Dim cells = a.Split(","c)
dgvOutput.Rows.Add(cells)
You would need to test your explicit circumstances to determine which is better for what you're trying to do.
Your loop is executed over all lines skipping just the first line.
While I cannot see what happen in the FileClose call it seems to not have any sense because ReadAllLines has already closed the file.
You can get the second line of your file with a single line of code
Dim line as String = File.ReadLines(OrderID & ".txt").Skip(1).Take(1).FirstOrDefault()
' this check is required to avoid problems with files containing 0 or 1 line
if line IsNot Nothing Then
Dim cells = line.Split(","c)
dgvOutput.Rows.Add(cells)
End If
Notice that I have replaced the ReadAllLines with ReadLines. This is better because using this method you don't read all lines when you need only the second one (if it exists). More info at ReadLines vs ReadAllLines
Dim lines = IO.File.ReadAllLines(OrderID & ".txt")
Dim SecondLine = lines(1)
File.ReadAllLines opens and closes the file for you so there is not need to add code to close it.
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.
New to VB.Net but a friend recommended that I used it for what I'm trying to do. I have a huge text file and I want to insert carriage returns in after a specific string.
Apart from the mess I have below , how would I alter this to read a file and then once we see the text "ext" insert a new line feed. I'm expecting one of the lines in the input file to produce alot of carriage returns.
Currently what I have managed to mock together below reads an input file until end of line and writes it out again into another file.
Module Module1
Sub Main()
Try
' Create an instance of StreamReader to read from a file.
' The using statement also closes the StreamReader.
Using sr As StreamReader = New StreamReader("C:\My Documents\input.txt")
Dim line As String
' Read and display lines from the file until the end of
' the file is reached.
Using sw As StreamWriter = New StreamWriter("C:\My Documents\output.txt")
Do Until sr.EndOfStream
line = sr.ReadLine()
sw.WriteLine(line)
Console.WriteLine("done")
Loop
End Using
End Using
Catch e As Exception
' Let the user know what went wrong.
Console.WriteLine("The file could not be read:")
Console.WriteLine(e.Message)
End Try
Console.ReadKey()
End Sub
Changes made following comments.. Falling over at 500mb files due to memory constraints:
Sub Main()
Try
' Create an instance of StreamReader to read from a file.
' The using statement also closes the StreamReader.
Using sr As StreamReader = New StreamReader("C:\My Documents\input.txt")
Dim line As String
Dim term As String = "</ext>"
' Read and display lines from the file until the end of
' the file is reached.
Using sw As StreamWriter = New StreamWriter("C:\My Documents\output.txt")
Do Until sr.EndOfStream
line = sr.ReadLine()
line = line.Replace(term, term + Environment.NewLine)
sw.WriteLine(line)
Console.WriteLine("done")
Loop
End Using
End Using
Since your lines are very big, you'll have to:
Read/Write one character at a time
Save the last x characters
If the last x characters are equal to your term, write a new line
Dim term As String = "</ext>"
Dim lastChars As String = "".PadRight(term.Length)
Using sw As StreamWriter = New StreamWriter("C:\My Documents\output.txt")
Using sr As New System.IO.StreamReader("C:\My Documents\input.txt")
While Not sr.EndOfStream
Dim buffer(1) As Char
sr.Read(buffer, 0, 1)
lastChars &= buffer(0)
lastChars = lastChars.Remove(0, 1)
sw.Write(buffer(0))
If lastChars = term Then
sw.Write(Environment.NewLine)
End If
End While
End Using
End Using
Note: This will not work with a Unicode file. This assume each characters are one byte.
I simply need to read lines from a text file and show them. When I run this I can see that id does what I want, but after it reads the last value it just shows a blank form on my screen and does not move on. It seems like it can't find the end of the file or something. I don't get an error.
Using sr As New System.IO.StreamReader(Application.StartupPath & "\myfile.cfg")
Dim Line As String = ""
Dim i As Integer = 0
Dim temp_array As Array
Do While Line IsNot Nothing
Line = sr.ReadLine
temp_array = Line.Split("=")
'MessageBox.Show(temp_array(0))
Loop
End Using
That is bad code because you're actually going to use Line before testing whether it's Nothing. Here are two good options for looping through the lines of a text file:
Using reader As New StreamReader(filePath)
Dim line As String
Do Until reader.EndOfStream
line = reader.ReadLine()
'...
Loop
End Using
For Each line In File.ReadLines(filePath)
'...
Next
As you can see, the second is far more concise but it does require .NET 4.0 or later.
Hey all i am trying to figure out a way to delete something inside a text file but keep everything around it.
An example of this would be:
SDfmifgn349234024jn4tnge0b04tnEFGm34tmn34t0egonkerglnk
318erg4nergpERGhmboergn4t34tmg054
fg94t34tskmsdglnEGgjr894ERG94mrg34tSDFS$45352ty
GGreerkg0gm4m505556g0fdg6555fbd105f1g
And say i wanted to delete the 318erg4nergpERGhmboergn4t34tmg054 and therefore it would turn out to be saved as:
SDfmifgn349234024jn4tnge0b04tnEFGm34tmn34t0egonkerglnk
fg94t34tskmsdglnEGgjr894ERG94mrg34tSDFS$45352ty
GGreerkg0gm4m505556g0fdg6555fbd105f1g
But i am unable to find out how to go about doing that!
I've tried this code below that i found:
Dim dir As New DirectoryInfo(defaultNetworkDrive)
For Each file As FileInfo In dir.GetFiles()
If file.Extension = ".txt" Then
Dim ioFile As New StreamReader(defaultNetworkDrive & file.Name)
Dim ioLine As String ' Going to hold one line at a time
Dim ioLines As String ' Going to hold whole file
ioLine = ioFile.ReadLine
ioLines = ioLine
While Not ioLine = ""
ioLine = ioFile.ReadLine
ioLines = ioLines & vbCrLf & ioLine
End While
MsgBox(ioLines) 'SHOWS all the lines in the TXT file
If InStr(1, ioLines, encryptedText, vbTextCompare) <> 0 Then
MsgBox("True")
Else
MsgBox("False")
End If
'Dim sw As StreamWriter = file.CreateText("input.txt")
'sw.Write(ioLines)
'sw.Close()
ioFile.Close()
End If
Next
I do find it and its TRUE but i am not sure how to go about just deleting that line then saving it!
Any help would be great! :o)
David
You have to rewrite the file. Use StreamWriter to create a temporary file. Read one line at a time and write it to the output file. Skip the write if you don't want the line. Clean up by renaming the original, renaming the temporary then deleting the renamed original.
Use something better than a text file, like a dbase, if this is too slow.
You need to check for the string to exclude inside the loop where you read the lines:
While Not ioLine = ""
ioLine = ioFile.ReadLine
If ioLine <> "318erg4nergpERGhmboergn4t34tmg054" then
ioLines = ioLines & vbCrLf & ioLine
End
End While
If ioLines.StartsWith(encryptedText) Then
MsgBox("True")
Else
MsgBox("False")
End If
You are checking if the 'file' (ioLines) starts with the encrypted text, not the line (ioLine). I suspect that's why it isn't finding it.
I'm not sure if you are intending it, but I think adding the vbCrLf to ioLines will cause an empty line between each line. So your file output would be
LINE
[empty line]
LINE
[empty line]
...
To save the file without that line, you would need to write the lines you want to save to a new file.
Read line from file
If not excluded line
write line
Something like that (obviously off the top of my head) :)
Hmm, maybe I found the answer.
You are connecting all lines together:
ioLines = ioLines & vbCrLf & ioLine
Later you are trying to find the search string, but only at the start of the combined line!
ioLines.StartsWith(encryptedText)
This would only find the encryptedText if it be appear on the very first line of the file.
In your example the relevant string is somewhere in the middle of the iolines string.
So you should try to use
ioLines.Contains(encryptedText)
instead.
Edit:
You could try to do the following (just a though, I haven't tested it)
Dim fileLines as List(Of String)
fileLines = new List(Of String)(File.ReadAllLines(yourFileNameHere))
For i as Integer = fileLines.Count To 0 Step -1
If fileLines(i).Contains(encryptedText) Then
fileLines(i).RemoveAt(i)
End If
Next
File.WriteAllLines(yourFileNameHere, fileLines.ToArray)
HTH