I want to know if it is possible to compute the name of a variable in VB.net. I need to open a bunch of text files at runtime. The exact number will be variable. I wanted to do something along the lines of:
For j = 1 to Filecount
Dim Filename As String = "File"&j
Dim File & j As New System.IO.StreamWriter(Filename)
Next
When I tried this, VB.net said it didn't like it. Is this possible?
I think you would be better off using a dictionary, which would allow you to get back to the appropriate stream writer using the filename later:
Dim fileDictoinary As New Dictionary(Of String, System.IO.StreamWriter)
For j = 1 To Filecount
Dim Filename As String = "File" & j
fileDictoinary.Add(Filename, New System.IO.StreamWriter(Filename))
Next
Then at a later time you can access the streamwriter using the filename in the dictionary:
Dim file4StreamWriter = fileDictoinary("File4")
file4StreamWriter.Write(True)
Related
I am trying to go through my text file and create a new file that will contain only the text I require. My current line looks like:
Car-1I
Colour-39
Cost-328
Dealer-28
Car-2
Colour-30
Cost-234
For each block of text I would like to read the first line, if the first line ends with an I, then read the next line, if that line contains a colour 39, then I would like to save the whole block of text to another file. If these two conditions aren't met, I dont want to save my values to the new text file.
Before anything about saving my values in classes are mentioned, these blocks of text can vary in size and values, so I dont always have a set range of values which is why i need to skip to the blank line
IO.File.WriteAllText("C:\Users\test2.txt", "") 'write to new file
Dim sKey As String
Dim sValue As Integer
For Each filterLine As String In File.ReadLines("C:\Users\test.txt")
sKey = Split(filterLine, ":")(0)
sValue = Split(filterLine, ":")(1)
If Not sValue.EndsWith("I") Then
ElseIf sValue.EndsWith("I") Then
End If
Next
Another method, using File.ReadLines to read lines of text from file. This method doesn't load all the text in memory, it reads from disc single lines of text, so it can also be useful when dealing with big files.
You could loop the IEnumerable collection it returns, but also use its GetEnumerator() method to control more directly when to move to the next line, or move more then one lines forward.
Its Enumerator.Current object returns the line of text currently read, Enumerator.MoveNext() moves to the next line.
A StringBuilder is used to store the strings when a match found. Strings are added to the StringBuilder object using its AppendLine() method.
This class is useful when dealing with strings that you need to store, compare and discard (or modify) quickly: since string are immutable, when you use String variables directly, especially in loops, you generate a whole lot of garbage that slows down any procedure quite a lot.
The blocks of text stored in the StringBuilder object are then written to a destination file using a StreamWriter with explicit encoding set to UTF-8 (writes the BOM). Its methods include asynchronous versions: WriteLine() can be replaced by awaitWriteLineAsync() to allow an async procedure.
Imports System.IO
Imports System.Text
Dim sourceFilePath = "<Path of the source file>"
Dim resultsFilePath = "<Path of the destination file>"
Dim sb As New StringBuilder()
Dim enumerator = File.ReadLines(sourceFilePath).GetEnumerator()
Using sWriter As New StreamWriter(resultsFilePath, False, Encoding.UTF8)
While enumerator.MoveNext()
If enumerator.Current.EndsWith("I") Then
sb.AppendLine(enumerator.Current)
enumerator.MoveNext()
If enumerator.Current.EndsWith("39") Then
While Not String.IsNullOrWhiteSpace(enumerator.Current)
sb.AppendLine(enumerator.Current)
enumerator.MoveNext()
End While
sWriter.WriteLine(sb.ToString())
End If
sb.Clear()
End If
End While
End Using
This will work:
Dim strFile As String = "c:\Test5\Source.txt"
Dim strOutFile As String = "c:\Test5\OutPut.txt"
Dim strOutData As String = ""
Dim SourceGroups As String() = Split(File.ReadAllText(strFile), vbCrLf + vbCrLf)
For Each sGroup As String In SourceGroups
Dim OneGroup() As String = Split(sGroup, vbCrLf)
If Strings.Right(OneGroup(0), 1) = "I" And (Strings.Right(OneGroup(1), 2) = "39") Then
If strOutData <> "" Then strOutData += (vbCrLf & vbCrLf)
strOutData += sGroup
End If
Next
File.WriteAllText(strOutFile, strOutData)
Something like this should work:
Dim base, i, c as Integer
Dim lines1$() = File.ReadLines("C:\Users\test.txt")
c = lines1.count
While i < c
if Len(RTrim(lines1(i))) Then
If Strings.Right(RTrim(lines1(i)), 1)="I" Then
base = i
i += 1
If Strings.Right(RTrim(lines1(i)), 2)="39" Then
While Len(RTrim(lines1(i))) 'skip to the next blank
i += 1
End While
' write lines1(from base to (i-1)) here
Else
While Len(RTrim(lines1(i)))
i += 1
End While
End If
Else
i += 1
End If
Else
i += 1
End If
End While
I am in need of assistance... i am trying to create a textfile with links in it. the code i have..
dim domain as string = "http://www.mywebsite/"
dim name as string = "username"
Dim link As String = New String("domain" & "name")
TextBox1.AppendText(link & Environment.NewLine)
Msgbox(textBox1.lines(0))
The problem is that MsgBox only shows up as "http://www.mywebsite/". the textbox does show "http://www.mywebsite/username" but when copied to text document it is:
Line0: http://www.mywebsite/
Line1:username
any ideas... tried using
Dim link As String = String.Join(domain & name) but that doesnt work nor does
Dim link As String = new String.Join(domain & name)
i need
Msgbox(textBox1.lines(0)) to display "http://www.mywebsite/username" not one or the other.
That was quick got a message saying to use. Dim link As String = String.Concat(domain & name)
i think you should move to StringBuilder first import Imports System.Text
'create a string with multiple lines
Dim a As New StringBuilder
a.AppendLine("hi")
a.AppendLine("there")
a.AppendLine("this")
a.AppendLine("is")
a.AppendLine("a")
a.AppendLine("test")
'read will makes read line by line
Dim read As String() = a.ToString.Split(vbNewLine)
'count has number of lines
Dim count As Integer = a.ToString().Split(vbNewLine).Length - 1
'lines will be added to combobox one by one
For i As Integer = 0 To count - 1
ComboBox1.Items.Add(read(i))
Next
you just should edit it to suits your needs i didnt understand what you needed exactly
I'm wondering if it's possible to rename all the files in a folder with a simple program, using vb.NET
I'm quite green and not sure if this is even possible.
Lets say there is a folder containing the files:
Text_Space_aliens.txt, fishing_and_hunting_racoons.txt and mapple.txt.
Using a few credentials:
Dim outPut as String = "TextFile_"
Dim fileType as String = ".txt"
Dim numberOfFiles = My.Computer.FileSystem.GetFiles(LocationFolder.Text)
Dim filesTotal As Integer = CStr(numberOfFiles.Count)
Will it be possible to rename these, regardless of previous name, example:
TextFile_1.txt, TextFile_2.txt & TextFile_3.txt
in one operation?
I think this should do the trick. Use Directory.GetFiles(..) to look for specific files. Enumerate results with a for..each and move (aka rename) files to new name. You will have to adjust sourcePath and searchPattern to work for you.
Private Sub renameFilesInFolder()
Dim sourcePath As String = "e:\temp\demo"
Dim searchPattern As String = "*.txt"
Dim i As Integer = 0
For Each fileName As String In Directory.GetFiles(sourcePath, searchPattern, SearchOption.AllDirectories)
File.Move(Path.Combine(sourcePath, fileName), Path.Combine(sourcePath, "txtFile_" & i & ".txt"))
i += 1
Next
End Sub
In your title you state something about chronologically, but within your question you never mentioned it again. So I did another example ordering files by creationTime.
Private Sub renameFilesInFolderChronologically()
Dim sourcePath As String = "e:\temp\demo"
Dim searchPattern As String = "*.txt"
Dim curDir As New DirectoryInfo(sourcePath)
Dim i As Integer = 0
For Each fi As FileInfo In curDir.GetFiles(searchPattern).OrderBy(Function(num) num.CreationTime)
File.Move(fi.FullName, Path.Combine(fi.Directory.FullName, "txtFile_" & i & ".txt"))
i += 1
Next
End Sub
I've never done Lambdas in VB.net but tested my code and it worked as intended. If anything goes wrong please let me know.
Been following the threads for sometime as a novice (more of a newbie) but am now starting to do more.
I can read how to open a text file but am having trouble understanding the .replace functionality (I get the syntax just can't get it to work).
Scenario:
Inputfile name = test_in.txt
replace {inputfile} with c:\temp\test1.txt
I'm using test.txt as a template for a scripting tool and need to replace various values within to a new file called test_2.txt.
I've got variables defining the input and output files without a problem, I just can't catch the syntax for opening the new file and replacing.
You really have not given us that much to go on. But a common mistake in using String.Replace is that it makes a copy of the source which needs to be saved to another variable or else it will go into the bit bucket. So in your case, something like this should work.
Dim Buffer As String 'buffer
Dim inputFile As String = "C:\temp\test.txt" 'template file
Dim outputFile As String = "C:\temp\test_2.txt" 'output file
Using tr As TextReader = File.OpenText(inputFile)
Buffer = tr.ReadToEnd
End Using
Buffer = Buffer.Replace("templateString", "Hello World")
File.WriteAllText(outputFile, Buffer)
Try something like this:
Dim sValuesToReplace() As String = New String() {"Value1", "Value2", "Value3"}
Dim sText As String = IO.File.ReadAllText(inputFilePath)
For Each elem As String In sValuesToReplace
sText = sText.Replace(elem, sNewValue)
Next
IO.File.WriteAllText(sOutputFilePath, sText)
It depends if you want to replace all values with only one value, or with different values for each. If you need different values you can use a Dictionary:
Dim sValuesToReplace As New Dictionary(Of String, String)()
sValuesToReplace.Add("oldValue1", "newValue1")
sValuesToReplace.Add("oldValue2", "newValue2")
'etc
And then loop throgh it with:
For Each oldElem As String In sValuesToReplace.Keys
sText = sText.Replace(oldElem, sValuesToReplace(oldElem))
Next
I am trying to run an event which will search through the different files in a given directory. The goal is to have it search for all files that begin with 'SP_', which are .sql files containing Stored Procedures. I would then like to add the full text of these Procedures to an array to be used later. This is causing an error when run, which I believe is because 'FullProcedureArray()', the string array I am trying to load does not have defined boundaries. When I declare it as 'FullProcedureArray(7)', or with some other value, it appears to run fine. But I don't want to have to hard-code a boundary for 'FullProcedureArray'; I would rather let it be defined by whatever the number of files in the folder is.
My question: Is there a way to declare 'FullProcedureArray' without having to give it an absolute value? I may just be missing something painfully obvious, but I haven't worked with this type of array much in the past. Thanks in advance for your help.
Dim AppDataLocation As String = "C:\Files\TestFiles\"
Dim ProcedureArray As String()
Dim ProcedureText As String
Dim FullProcedureArray() As String
Dim sourceDirectoryInfo As New System.IO.DirectoryInfo(AppDataLocation)
Dim fileSystemInfo As System.IO.FileSystemInfo
Dim i As Integer = 0
For Each fileSystemInfo In sourceDirectoryInfo.GetFileSystemInfos
If (fileSystemInfo.Name.Contains("SP_")) Then
ProcedureArray = System.IO.File.ReadAllLines(AppDataLocation & fileSystemInfo.Name)
ProcedureText = Join(ProcedureArray, "")
FullProcedureArray.SetValue(ProcedureText, i)
i = (i + 1)
End If
Next
An array by definition has a fixed upper bound. If you don't want a fixed upper bound, don't use an array. Use, for example, a List(Of String) instead:
Dim AppDataLocation As String = "C:\Files\TestFiles\"
Dim ProcedureList As New List(Of String)
Dim sourceDirectoryInfo As New System.IO.DirectoryInfo(AppDataLocation)
For Each fileSystemInfo As System.IO.FileSystemInfo In sourceDirectoryInfo.GetFileSystemInfos
If (fileSystemInfo.Name.Contains("SP_")) Then
Dim ProcedureText As String = _
System.IO.File.ReadAllText(AppDataLocation & fileSystemInfo.Name)
ProcedureList.Add(ProcedureText)
End If
Next
If, for some reason, you still need the result as an array afterwards, simply convert the list to an array:
Dim myArray() As String = ProcedureList.ToArray()
If you don't want to give a size to your array or want to change at runtime, you can use "Redim Preserve"
http://msdn.microsoft.com/en-us/library/w8k3cys2%28v=vs.71%29.aspx