HI have a Program that loops through a text file and reads the lines.
Using r As StreamReader = New StreamReader("C:\test.txt")
Dim lineCount = File.ReadAllLines("C:\test.txt").Length
MsgBox(lineCount)
For x = 1 to linecount
line = r.ReadLine
msgbox (line)
next
How can I read the Left most 15 characters of each line of the text file, ignoring the other characters in each line. Lastly, if there are spaces in the first 15 characters, i'd like to remove them.
Calling ReadAllLines to discover how many lines are there to drive a for..loop is wrong and a waste of resources (Essentially you are reading all the file content two times). In particular consider that a StreamReader has a method that tells you if you have reached the end of file
So everything could be changed to a simpler
Dim clippedLines = new List(Of String)()
Dim line As String
Using r As StreamReader = New StreamReader("C:\test.txt")
While r.Peek() >= 0
line = r.ReadLine
Dim temp = if(line.Length > 15, line.Substring(0,15), line)
clippedLines.Add(temp.Trim().Replace(" "c, ""))
End While
End Using
This will remove all the spaces from the line AFTER taking the first 15 char (and thus the result could be a string shorter than 15 chars) If you want a line of 15 char after the space removing operation, then
While r.Peek() >= 0
line = r.ReadLine.Trim().Replace(" "c, "")
Dim temp = if(line.Length > 15, line.Substring(0,15), line)
clippedLines.Add(temp)
End While
Related
I'm looking to read lines from a text file that start with certain characters and stop when the line starts with other characters. So in my example I would like to start reading at line AB and stop at line EF however not all lines will contain the CD line. There will always be a AB line and EF line, however the number of lines in between is unknown.
Here is an example of the lines in a text file I would be reading. You can see that this will create two rows in the DataGridView however the first row is missing the CD line and should be blank.
AB-id1
EF-address1
AB-id2
CD-name1
EF-address2
Here is the code I have so far:
Dim lines() As String = File.ReadAllLines(textfile)
For i As Integer = 0 To lines.Length - 1
If lines(i).StartsWith("AB") Then
Dim nextLines As String() = lines.Skip(i + 1).ToArray
Dim info As String = nextLines.FirstOrDefault(Function(Line) Line.StartsWith("CD"))
Dim name As String = "Yes"
Dim info2 As String = nextLines.FirstOrDefault(Function(Line) Line.StartsWith("EF"))
Dim address As String = "Yes"
End If
DataGridView.Rows.Add(name,address)
Next
Now the output I currently get is:
|Yes|Yes|
|Yes|Yes|
And I should be getting:
||Yes|
|Yes|Yes|
It looks like it's reading too far down the text file and I need it to stop reading at EF. I've tried Do while and Do Until with no success. Any suggestions?
You could use the Array.FindIndex function to get the index of the next line starting with your prefix. This way you don't have to skip lines and create a new array each time.
Try this out instead:
Dim lines() As String = File.ReadAllLines(textFile)
For i As Integer = 0 To lines.Length - 1
If lines(i).StartsWith("AB") Then
Dim addressIndex As Integer = Array.FindIndex(lines, i + 1, Function(Line) Line.StartsWith("EF"))
Dim address As String = If(addressIndex <> -1, lines(addressIndex).Substring(3), "") ' Get everything past the "-"
Dim name As String = ""
If addressIndex <> -1 Then
Dim nameIndex As Integer = Array.FindIndex(lines, i + 1, addressIndex - i, Function(line) line.StartsWith("CD"))
If nameIndex <> -1 Then
name = lines(nameIndex).Substring(3) ' Get everything past the "-"
End If
End If
DataGridView.Rows.Add(name, address)
End If
Next
I have this code but it have errors , what should i do ?
Dim lines As New List(Of String)
lines = RichTextBox1.Lines.ToList
'Dim FilterText = "#"
For i As Integer = lines.Count - 1 To 0 Step -1
'If (lines(i).Contains(FilterText)) Then
RichTextBox1.Lines(i) = RichTextBox1.Lines(i).Replace("#", "#sometext")
'End If
Next
RichTextBox1.Lines = lines.ToArray
Update: while the following "works" it does only modify the array which was returned from the Lines-property. If you change that array you don't change the text of the TextBox. So you need to re-assign the whole array to the Lines-property if you want to change the text(as shown below). So i keep the first part of my answer only because it fixes the syntax not the real issue.
It's not
RichTextBox1.Lines(i).Replace = "#sometext"
but
RichTextBox1.Lines(i) = "#sometext"
You can loop the Lines forward, the reverse loop is not needed here.
Maybe you want to replace all "#" with "#sometext" instead:
RichTextBox1.Lines(i) = RichTextBox1.Lines(i).Replace("#","#sometext")
So here the full code necessary (since it still seems to be a problem):
Dim newLines As New List(Of String)
For i As Integer = 0 To RichTextBox1.Lines.Length - 1
newLines.Add(RichTextBox1.Lines(i).Replace("#", "#sometext"))
Next
RichTextBox1.Lines = newLines.ToArray()
But maybe you could even use:
RichTextBox1.Text = RichTextBox1.Text.Replace("#","#sometext")`
because if we have # abcd this code change it to # sometextabcd ! I
Want a code to replace for example line 1 completely to # sometext
Please provide all relevant informations in the first place next time:
Dim newLines As New List(Of String)
For Each line As String In RichTextBox1.Lines
Dim newLine = If(line.Contains("#"), "#sometext", line)
newLines.Add(newLine)
Next
RichTextBox1.Lines = newLines.ToArray()
It's been a long time since I've programmed. I'm writing a form in VB.NET, and using StreamReader to read a text file and populate an 2D array. Here is the text file:
あかさたなはまやらわん
いきしちにひみ り
うくすつぬふむゆる
えけせてねへめ れ
おこそとのほもよろを
And here is the loop, which is within the Load event.
Dim Line As String
Dim Row As Integer = 0
Using sReader As New IO.StreamReader("KanaTable.txt")
Do
Line = sReader.ReadLine
For i = 0 To Line.Length - 1
KanaTable(Row, i) = Line(i)
Next
Row += 1
Loop Until sReader.EndOfStream
End Using
The problem is, once the i in the For Loop reaches 10, it completes the loop and skips the other lines, even when I have a breakpoint. Can you let me know what's probably going on here?
I've figured out the problem, it was very simple. The array declaration for KanaTable:
Dim KanaTable(4, 9) As Char
should have been
Dim KanaTable(4, 10) As Char
Because there was one less space in the array than there should have been, the debugger must have been throwing an IndexOutOfRange which I couldn't see, because, stupid Windows bug (thanks to Bradley Uffner for pointing out this bug.)
If you can use an array of arrays or a list of arrays (List(Of Char())), you can get this down to a single line of code:
Dim KanaTable()() As Char = IO.File.ReadLines("KanaTable.txt").Select(Function(line) line.ToCharArray()).ToArray()
If that's too complicated for you, we can at least simplify the existing code:
Dim KanaTable As New List(Of Char())
Dim Line As String
Using sReader As New IO.StreamReader("KanaTable.txt")
Line = sReader.ReadLine()
While Line IsNot Nothing
KanaTable.Add(Line.ToCharArray())
Line = sReader.ReadLine()
End While
End Using
I can't see an error immediately, but you could try to adapt your code to this:
Using reader As New IO.StreamReader("KanaTable.txt")
Do
line= reader.ReadLine()
If line = Nothing Then
Exit Do
End If
For i = 0 To Line.Length - 1
KanaTable(Row, i) = Line(i)
Next
Row += 1
Loop
End Using
I'm creating a program that is supposed to enter text from file ( in .txt format) to Textbox1 when Button1 action clicked. But reading must start after line 6 (in 1,2,3,4,5,6 notation) or after line 5 (in 0,1,2,3,4,5 notation) and it should last till end of the file.
Use
File.ReadLines("C:\data\text.txt")
and bypass the lines you don´t need
Dim Lines = File.ReadLines("C:\data\text.txt")
Dim sb As New StringBuilder()
' Start on Line 7 To Last Line
For i As Long = 7 To Lines.Count
Dim line as String = Lines(i)
sb.AppendLine(line)
Next
MessageBox.Show(sb.ToString())
I would ask if you could give me some alternatives in my problems.
basically I'm reading a .txt log file averaging to 8 million lines. Around 600megs of pure raw txt file.
I'm currently using streamreader to do 2 passes on those 8 million lines doing sorting and filtering important parts in the log file, but to do so, My computer is taking ~50sec to do 1 complete run.
One way that I can optimize this is to make the first pass to start reading at the end because the most important data is located approximately at the final 200k line(s) . Unfortunately, I searched and streamreader can't do this. Any ideas to do this?
Some general restriction
# of lines varies
size of file varies
location of important data varies but approx at the final 200k line
Here's the loop code for the first pass of the log file just to give you an idea
Do Until sr.EndOfStream = True 'Read whole File
Dim streambuff As String = sr.ReadLine 'Array to Store CombatLogNames
Dim CombatLogNames() As String
Dim searcher As String
If streambuff.Contains("CombatLogNames flags:0x1") Then 'Keyword to Filter CombatLogNames Packets in the .txt
Dim check As String = streambuff 'Duplicate of the Line being read
Dim index1 As Char = check.Substring(check.IndexOf("(") + 1) '
Dim index2 As Char = check.Substring(check.IndexOf("(") + 2) 'Used to bypass the first CombatLogNames packet that contain only 1 entry
If (check.IndexOf("(") <> -1 And index1 <> "" And index2 <> " ") Then 'Stricter Filters for CombatLogNames
Dim endCLN As Integer = 0 'Signifies the end of CombatLogNames Packet
Dim x As Integer = 0 'Counter for array
While (endCLN = 0 And streambuff <> "---- CNETMsg_Tick") 'Loops until the end keyword for CombatLogNames is seen
streambuff = sr.ReadLine 'Reads a new line to flush out "CombatLogNames flags:0x1" which is unneeded
If ((streambuff.Contains("---- CNETMsg_Tick") = True) Or (streambuff.Contains("ResponseKeys flags:0x0 ") = True)) Then
endCLN = 1 'Value change to determine end of CombatLogName packet
Else
ReDim Preserve CombatLogNames(x) 'Resizes the array while preserving the values
searcher = streambuff.Trim.Remove(streambuff.IndexOf("(") - 5).Remove(0, _
streambuff.Trim.Remove(streambuff.IndexOf("(")).IndexOf("'")) 'Additional filtering to get only valuable data
CombatLogNames(x) = search(searcher)
x += 1 '+1 to Array counter
End If
End While
Else
'MsgBox("Something went wrong, Flame the coder of this program!!") 'Bug Testing code that is disabled
End If
Else
End If
If (sr.EndOfStream = True) Then
ReDim GlobalArr(CombatLogNames.Length - 1) 'Resizing the Global array to prime it for copying data
Array.Copy(CombatLogNames, GlobalArr, CombatLogNames.Length) 'Just copying the array to make it global
End If
Loop
You CAN set the BaseStream to the desired reading position, you just cant set it to a specfic LINE (because counting lines requires to read the complete file)
Using sw As New StreamWriter("foo.txt", False, System.Text.Encoding.ASCII)
For i = 1 To 100
sw.WriteLine("the quick brown fox jumps ovr the lazy dog")
Next
End Using
Using sr As New StreamReader("foo.txt", System.Text.Encoding.ASCII)
sr.BaseStream.Seek(-100, SeekOrigin.End)
Dim garbage = sr.ReadLine ' can not use, because very likely not a COMPLETE line
While Not sr.EndOfStream
Dim line = sr.ReadLine
Console.WriteLine(line)
End While
End Using
For any later read attempt on the same file, you could simply save the final position (of the basestream) and on the next read to advance to that position before you start reading lines.
What worked for me was skipping first 4M lines (just a simple if counter > 4M surrounding everything inside the loop), and then adding background workers that did the filtering, and if important added the line to an array, while main thread continued reading the lines. This saved about third of the time at the end of a day.