i am trying to split a string up into separate lines with the following code, but for some reason it is also removing the spaces in the string.
Dim calculationText As String
calculationText = File.ReadAllText(fileName)
Dim fields() As String
fields = calculationText.Split(vbCrLf)
when i am in debugger mode, i look at fields, and every element has a line of the string but all the spaces and tabs are removed.
any reason for this?
If you are reading from a file, can you use:
Sub Main()
Dim fields As New List(Of String)
' read file into list
Using sr As System.IO.StreamReader = My.Computer.FileSystem.OpenTextFileReader(filename)
Try
Do While sr.Peek() >= 0
fields.Add(sr.ReadLine())
Loop
Finally
If sr IsNot Nothing Then sr.Close()
End Try
End Using
' check results
For Each line As String In fields
Console.WriteLine(line)
Next
End Sub
How 'bout:
Dim fields() As String = File.ReadAllLines(fileName)
As for why string.Split() is doing weird things...
vbCrLf is a string, and there's not an overload for string.split that accepts a single string parameter. If he were to turn on Option Explicit it wouldn't even compile, but since it's off, vbCrLf can be interpreted as an array of characters. And in this code, that's exactly what happens:
Sub Main()
Dim z As String = "The quick brown" & vbCrLf & " fox jumps over the lazy dogs."
Dim a() As String = z.Split(vbCrLf)
For Each c As String In a
Console.WriteLine(c)
Next
Console.ReadKey(True)
End Sub
You'll see two line breaks between the 1st and 2nd parts of that string. Something else is stripping out the spaces. Can you share the larger code block?
Gotta say I've never seen it do that, and I've used String.Split extensively. Are they really really gone, or is it a trick of the debugger?
There's not actually any .Split method that takes one string as the parameter, so the VB compiler would be doing "things" behind the scenes to pick a different overload. To try and force the correct overload, you could try calculationText.Split(vbCrLf.ToCharArray()). I doubt it will help, but you never know :-)
Related
This is the first challenge on Day 1 of the 2018 Advent of Code
(link: https://adventofcode.com/2018/day/1)
So I am trying to create a program that reads a long list of positive and negative numbers (e.g +1, -2, +3, etc.) and then add them up to create a total. I have researched some methods of file handling in Visual Basic, and have come up with the below method:
Sub Main()
Dim objStreamReader As StreamReader
Dim strLine As String = ""
Dim total As Double = 0
objStreamReader = New StreamReader(AppDomain.CurrentDomain.BaseDirectory & "frequencies.txt")
strLine = objStreamReader.ReadLine
Do While Not strLine Is Nothing
Console.WriteLine(strLine)
strLine = objStreamReader.ReadLine
total += strLine
Loop
Console.WriteLine(total)
objStreamReader.Close()
Console.ReadLine()
End Sub
Here is a link to the list of numbers: https://adventofcode.com/2018/day/1/input
It is not a syntax error I am getting but a logic error. The answer is somehow wrong, but I cannot seem to figure out where! I have tried to remove the signs from each number but that throws me a NullException error when it compiles.
So far I have come out with the answer 549, which the Advent of Code webiste rejects. Any ideas?
Make your life easier by using File.ReadLines(fileName) instead of dealing with StreamReader. Use Path.Combine instead of string concatenation to create a path. Path.Combine takes care of adding missing \ or removing extra ones etc.
Your file might contain an extra empty line at its end, that does not convert to a number. Use Double.TryParse to make sure you have a valid number before totalizing it. You should have Option Strict On anyway to enforce explicit conversions.
Dim fileName = Path.Combine(AppDomain.CurrentDomain.BaseDirectory, "frequencies.txt")
Dim total As Double = 0
For Each strLine As String In File.ReadLines(fileName)
Console.WriteLine(strLine)
Dim n As Double
If Double.TryParse(strLine, n) Then
total += n
End If
Next
Console.WriteLine(total)
Console.ReadLine()
For appending two string, please use string builder.
Dim test as new stringbuilder()
Test.append("your string")
It will not affect performance.
start=AKS-RHzlSXSftLGYdBNk.eyJhbGdvcml0aG0iOiJITUFDLVNIQTI1&
For every instance of the word 'start' I need to be able to get the text after the first full stop, right up until the & symbol. E.g. 'eyJhbGdvcml0aG0iOiJITUFDLVNIQTI1'.
There will be more than one instance of this. They will need to be appended to a listbox.
What is the simplest/quickest way to do this? (Using possibly streamreader - text file)
The simplest and quickest way will be to read each line, and check if it .StartsWith("start="). If so, then get the .IndexOf(".") and the .IndexOf("&", <whereever the first indexOf was>). Get the .SubString which encompasses those two values. I'm sure you can write the code yourself from that ;)
I tested this function with a button click, output text each line on a textbox. I am sure you can adapt this to your code.
Private Sub Button_Click(sender As Object, e As RoutedEventArgs)
txtResults.Text = ""
Dim ParseString As String
ParseString = "start=123341.23124&kjdshfkjsdaksdstart=1231.2321312&kadhskjashdkjastart=1231.23126789898&skjdfhkjsd"
Dim Delimiters() As String = New String() {"start="}
Dim Words() As String
Words = ParseString.Split(Delimiters, CompareMethod.Text)
For Each Part In Words
Dim Middle As String
Middle = Part.Split(".").Skip(1).Take(1).FirstOrDefault()
Dim Good As String
Good = Middle.Split("&").FirstOrDefault()
txtResults.Text += Good + vbNewLine
Next
End Sub
Output was
23124
2321312
23126789898
Added 31104 lines to a string and ran, took about 11 seconds to run on my laptop. Might be too slow for your app?
I'm trying to delete a selected row, then save the rest into a file. However, when I save it, it totally empties the file.
Console.Write("Please eneter the first name of the student you wish to search for: ")
searchfname = Console.ReadLine
searchfname = StrConv(searchfname, VbStrConv.ProperCase)
Console.Write("Please enter the second name of the student you wish to search for: ")
searchsname = Console.ReadLine
searchsname = StrConv(searchsname, VbStrConv.ProperCase)
Dim foundItem() As String = Nothing
Dim foundline As String = Nothing
Dim fnsearch As String = String.Join(searchfname, searchsname)
Dim lines As New List(Of String)(File.ReadAllLines("F:\Computing\Spelling Bee\stdnt&staffdtls.csv"))
For Each line As String In lines
If searchfname = item(3) And searchsname = item(4) Then
Console.WriteLine(line)
Console.WriteLine()
Console.WriteLine("Are you sure you wish to delete this record? (y/n)")
End If
Dim answer As String
answer = Console.ReadLine
If answer = "y" Or answer = "Y" Then
Console.Clear()
lines.Remove(line)
Using sw As New StreamWriter("F:\Computing\Spelling Bee\stdnt&staffdtls.csv")
sw.WriteLine(lines.ToString)
End Using
ElseIf answer = "n" Or answer = "N" Then
staffmenu()
End If
Next
Look at this line in your code:
sw.WriteLine(lines.ToString)
Extract the lines.ToString expression from that statement. The result of that expression is "System.String". You are telling your stream writer to write the text "System.String" to the file.
To fix it, you need something more like this:
Using sw As New StreamWriter("F:\Computing\Spelling Bee\stdnt&staffdtls.csv")
For Each line As String In lines
sw.WriteLine(line)
Next line
End Using
The method List(Of T).ToString does not produce a value that includes the elements of the collection. Instead it will just return the type name.
The API you are looking for is File.WriteAllLines. Using this instead of StreamWriter and the Using block
File.WriteAllLines("F:\Computing\Spelling Bee\stdnt&staffdtls.csv", lines)
I can see that this issue can be resolved from the given answers and comment, but I would like to add an alternative to use Join function in writing to a file. Try like this may be of help:
Using sw As New StreamWriter(.....)
sw.WriteLine(Join(lines.ToArray(), Environment.NewLine))
End Using
Since using VB.Net, this is a vb.net specific solution can not be used in C#. For C#, use string.join instead.
Hope it helps too!
Does anybody know how to lowercase the first word for each line in a textbox?
Not the first letter, the first word.
I tried like this but it doesn't work:
For Each iz As String In txtCode.Text.Substring(0, txtCode.Text.IndexOf(" "))
iz = LCase(iz)
Next
When you call Substring, it is making a copy of that portion of the string and returning it as a new string object. So, even if you were successfully changing the value of that returned sub-string, it still would not change the original string in the Text property.
However, strings in .NET are immutable reference-types, so when you set iz = ... all you are doing is re-assigning the iz variable to point to yet another new string object. When you set iz, you aren't even touching the value of that copied sub-string to which it previously pointed.
In order to change the value of the text box, you must actually assign a new string value to its Text property, like this:
txtCode.Text = "the new value"
Since that is the case, I would recommend building a new string, using a StringBuilder object, and then, once the modified string is complete, then set the text box's Text property to that new string, for instance:
Dim builder As New StringBuilder()
For Each line As String In txtCode.Text.Split({Environment.NewLine}, StringSplitOptions.None)
' Fix case and append line to builder
Next
txtCode.Text = builder.ToString()
The solutions here are interesting but they are ignoring a fundamental tool of .NET: regular expressions. The solution can be written in one expression:
Dim result = Regex.Replace(txtCode.Text, "^\w+",
Function (match) match.Value.ToLower(), RegexOptions.Multiline)
(This requires the import System.Text.RegularExpressions.)
This solution is likely more efficient than all the other solutions here (It’s definitely more efficient than most), and it’s less code, thus less chance of a bug and easier to understand and to maintain.
The problem with your code is that you are running the loop only on each character of the first word in the whole TextBox text.
This code is looping over each line and takes the first word:
For Each line As String In txtCode.Text.Split(Environment.NewLine)
line = line.Trim().ToLower()
If line.IndexOf(" ") > 0 Then
line = line.Substring(0, line.IndexOf(" ")).Trim()
End If
// do something with 'line' here
Next
Loop through each of the lines of the textbox, splitting all of the words in the line, making sure to .ToLower() the first word:
Dim strResults As String = String.Empty
For Each strLine As String In IO.File.ReadAllText("C:\Test\StackFlow.txt").Split(ControlChars.NewLine)
Dim lstWords As List(Of String) = strLine.Split(" ").ToList()
If Not lstWords Is Nothing Then
strResults += lstWords(0).ToLower()
If lstWords.Count > 1 Then
For intCursor As Integer = 1 To (lstWords.Count - 1)
strResults += " " & lstWords(intCursor)
Next
End If
End If
Next
I used your ideas guys and i made it up to it like this:
For Each line As String In txtCode.Text.Split(Environment.NewLine)
Dim abc() As String = line.Split(" ")
txtCode.Text = txtCode.Text.Replace(abc(0), LCase(abc(0)))
Next
It works like this. Thank you all.
I have an application which creates a list from items in a collection. Then for each item, I will add it to an empty string, then add a newline character to the end of it. So ideally my string will look something like:
List1\nList2\nList3\n
Once this string is generated, I send it back to be placed in a placeholder for a pdf. If I try this code in a simple console application, it prints everything on a newline. But in my real world situation, I have to print it to a pdf. The items only show up with spaces in between them and not newlines. How can can format my strings so that pdf recognizes the newline symbol rather than ignoring it?
Here is my code that generates the string with newlines.
Private Function ConcatPlacardNumbers(ByVal BusinessPlacardCollection As BusinessPlacardCollection) As String
Dim PlacardNumbersList As String = Nothing
Dim numberofBusinessPlacards As Long = BusinessPlacardCollection.LongCount()
For Each BusinessPlacard As BusinessPlacard In BusinessPlacardCollection
numberofBusinessPlacards = numberofBusinessPlacards - 1
PlacardNumbersList = String.Concat(PlacardNumbersList, BusinessPlacard.PlacardNumber)
If numberofBusinessPlacards <> 0 Then
PlacardNumbersList = String.Concat(PlacardNumbersList, Enviornment.newline)
End If
Next
Return PlacardNumbersList
End Function
Try to add \u2028 instead:
Private Function ConcatPlacardNumbers(ByVal BusinessPlacardCollection As _
BusinessPlacardCollection) As String
Dim PlacardNumbersList As New StringBuilder()
For Each BusinessPlacard As BusinessPlacard In BusinessPlacardCollection
PlacardNumbersList.Append(BusinessPlacard.PlacardNumber)
'PlacardNumbersList.Append(ChrW(8232)) '\u2028 line in decimal form
PlacardNumbersList.Append(ChrW(8233)) '\u2029 paragr. in decimal form
Next
Return PlacardNumbersList.ToString
End Function
For paragraphs use \u2029instead. Fore more details:
http://blogs.adobe.com/formfeed/2009/01/paragraph_breaks_in_plain_text.html
The answer will depend on the tool that is being used to produce the PDF. Since newline doesn't work, I would actually try \n. The other possibility is that the PDF generation code is not designed to emit multiple lines; you can only determine this by examining the generation code.
However, there is a significant performance issue that you should address in your code: you will be generating a lot of string objects using this code. You should change the design to use System.Text.StringBuilder, which will greatly improve the performance:
Private Function ConcatPlacardNumbers(ByVal BusinessPlacardCollection As BusinessPlacardCollection) As String
Dim PlacardNumbersList As New System.Text.StringBuilder(10000)
For Each BusinessPlacard As BusinessPlacard In BusinessPlacardCollection
If PlacardNumbersList.Length <> 0 Then
' This is equivalent to Environment.NewLine
'PlacardNumbersList.AppendLine()
' The attempt to use \n
PlacardNumbersList.Append("\n")
End If
PlacardNumbersList.Append(BusinessPlacard.PlacardNumber)
Next
Return PlacardNumbersList.ToString
End Function
Note that you also do not need to keep track of the placard number: you can add a newline to the end of the previous item on each pass after the first one.