I am using indexOf but I cannot figure out where I made a mistake as the output gives a -1.
I realise I can copy the whole statement paragraph into the last line of the output but I was hoping it could pull it straight from the label.
Public Class Form1
Private Sub btnCompute_Click(sender As Object, e As EventArgs) Handles btnCompute.Click
Dim statement As String
Dim letter As String
statement = CStr(lblStatement.Text)
letter = CStr(txtLetter.Text)
txtOutput.Text = CStr(lblStatement.Text).IndexOf("letter")
'txtOutput.Text = letter.ToUpper & " first occurs in position " & statement.IndexOf(statement) & "."
End Sub
End Class
Here is a picture of the form:
Update: Thanks to #ADyson and #Slugsie for taking the time to respond to my call for help. As #Slugsie noted it was indeed down to the lower case in my screenshot. I am now researching how to make it work without being case-sensitive.
Final code
Public Class Form1
Private Sub btnCompute_Click(sender As Object, e As EventArgs) Handles btnCompute.Click
txtOutput.Text = lblStatement.Text.IndexOf((txtLetter.Text).ToUpper)
End Sub
End Class
.IndexOf("letter")
is looking for the literal text letter within the data the user enters in the text. in VB.NET (and most other programming languages), anything enclosed within quote marks is treated as a fixed string of text, to be interpreted as-is rather than processed or treated as program code.
To make it look for the contents of the letter variable instead (which looks like what you were intending) simply remove the quote marks:
.IndexOf(letter)
As an aside, your whole code could be much reduced - primarily the use of CStr is unnecessary, because the Text properties of the textbox and label already return a string - meaning you don't need to use CStr convert it - and also because you're not making use of all the variables you declared either.
You could re-write your whole sample much more succinctly as:
Public Class Form1
Private Sub btnCompute_Click(sender As Object, e As EventArgs) Handles btnCompute.Click
txtOutput.Text = lblStatement.Text.IndexOf(txtLetter.Text)
End Sub
End Class
Related
I am writing some code in VB.Net to subtract one string from another string, but this is not working. in output nothing is changed in the target string. But there is no error message. Please help. Thanks.
If RadioButton1.Checked Then
TextBox1.Text = ""
positive = (TextBoxp1.Text + TextBoxp2.Text + TextBoxp3.Text)
negative = (TextBoxn1.Text + TextBoxn2.Text + TextBoxn3.Text)
findstring = Replace(positive, negative, "")
TextBox1.Text = findstring
End If
The concatenation symbol in vb.net is the ampersand (&). You may get unexpected results it you use the plus sign and the strings contain numbers. Parenthesis are not necessary to evaluate an expression except to establish order of calculation when it conflicts with order of precedence.
You are using the vb.net Strings.Replace method. I would use the .net String.Replace method because it is easier to move between .net languages when you get used to using .net methods instead of vb specific methods.
This method takes the original string in this case negative and looks for the entire positive string. If it finds the entire string it replaces it with the empty string.
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles Button1.Click
Dim positive = "b" & "cd" & "ef"
Dim negative = "abc" & "def" & "ghi"
TextBox1.Text = negative.Replace(positive, "")
'Result is aghi
End Sub
If you are trying to remove individual letters from a string then you will have to use a loop. Luckily for us a String is an array of Char.
Private Sub Button2_Click(sender As Object, e As EventArgs) Handles Button2.Click
Dim positive = "ceg"
Dim negative = "abcdefg"
For Each ch As Char In positive
negative = negative.Replace(ch, "")
Next
TextBox1.Text = negative
'Result abdf
End Sub
You are making this way too complicated. If what you want is to remove a substring from within a string use replace like this:
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles btnRemove.Click
If rdbtnRemove.Checked Then
txtResultString.Text = Replace(txtLargeString.Text, txtSearchString.Text, "")
End If
End Sub
All you need is two radio buttons, three text boxes and a button. If you enter 1121221114141 in the txtLargeString text box, 2122 in the txtSearchString text box and execute the code, the result is 111114141 which is the result of removing the txtSearchString input from the txtLargeString input.
Or if as #Mary suggested you want to use the more modern version of replace use this code:
Private Sub Button1_Click(sender As Object, e As EventArgs) Handles btnRemove.Click
If rdbtnRemove.Checked Then
txtResultString.Text = txtLargeString.Text.Replace(txtSearchString.Text, "")
End If
End Sub
I am working on a little morse code translation project and I cannot figure out how to detect when a certain key is in a textbox and replace it with the corresponding morse code dots and dashes in the correct spot.
For example if you type in "a b c" then i would like the program to check and put
".- -... -.-."
but it also needs to be dynamic so if you change up the order of your letters it can update the translation.
as of right now i have a key checking system where you can only type in one forward line and if you mess up you have to clear the whole box. thank you!
Here is a basic example of what I was suggesting in my comments above, i.e. using two separate TextBoxes and translating the whole text every time:
Private morseCodeDictionary As New Dictionary(Of Char, String) From {{"a"c, ".-"},
{"b"c, "-..."},
{"c"c, "-.-."}}
Private Sub inputTextBox_TextChanged(sender As Object, e As EventArgs) Handles inputTextBox.TextChanged
outputTextBox.Text = String.Join(" ",
inputTextBox.Text.
ToLower().
Select(Function(ch) morseCodeDictionary(ch)))
End Sub
Here's an implementation that doesn't use LINQ, so may be more understandable:
Private Sub inputTextBox_TextChanged(sender As Object, e As EventArgs) Handles inputTextBox.TextChanged
Dim characterStrings As New List(Of String)
For Each ch As Char In inputTextBox.Text
characterStrings.Add(morseCodeDictionary(ch))
Next
outputTextBox.Text = String.Join(" ", characterStrings)
End Sub
I have my frmMainwhich has RichTextBox1 and I have a button btnfind&Replacewhich whose click event pops out another minute form frmFindandReplace which has two textboxes: TextBoxSearch and TextBoxReplace with two buttons: replaceButton and findButton. I cannot seem to get my code for instances of finding a word in textbox and an instance of replacing it. Here is my code:
Public Class frmFindandReplace
Dim txtClientArea As RichTextBox
Private Sub TextBoxSearch_TextChanged(sender As Object, e As EventArgs) Handles TextBoxSearch.TextChanged
End Sub
Private Sub frmFindandReplace_Load(sender As Object, e As EventArgs) Handles MyBase.Load
End Sub
Private Sub replaceButton_Click(sender As Object, e As EventArgs) Handles replaceButton.Click
End Sub
Protected Friend Sub findButton_Click(sender As Object, e As EventArgs) Handles findButton.Click
Dim a As String
Dim b As String
a = TextBoxSearch.Text
b = InStr(StartPosition, a, txtClientArea)
If b Then txtClientArea.Focus()
txtClientArea.SelectionStart = b - 1
txtClientArea.SelectionLength = Len(a)
txtClientArea.ScrollToCaret()
End Sub
The findButton code doesnot even work. Throws an error!
Error 3: Overload resolution failed because no accessible 'InStr' can be called with these arguments:
'Public Function InStr(Start As Integer, String1 As String, String2 As String, [Compare As Microsoft.VisualBasic.CompareMethod = Microsoft.VisualBasic.CompareMethod.Binary]) As Integer': Value of type 'System.Windows.Forms.TextBox' cannot be converted to 'String'.
'Public Function InStr(String1 As String, String2 As String, [Compare As Microsoft.VisualBasic.CompareMethod = Microsoft.VisualBasic.CompareMethod.Binary]) As Integer': Value of type 'System.Windows.Forms.RichTextBox' cannot be converted to 'Microsoft.VisualBasic.CompareMethod'. C:\Users\Joseph GodwinKE\Documents\Visual Studio 2013\Projects\simpleapp\frmFindandReplace.VB 25 13 Simple app
I know I have not done much but am new and all my efforts of searching a solution over the internet have failed! Thank you I hope someone will help me pls.
A few pointers:
InStr returns an integer.
Check the documentation as it'll show you have the search values the wrong way around.
Turn Option Explicit on to help find your issues.
This should work better.
Private Sub findButton_Click(sender As Object, e As EventArgs) Handles findButton.Click
Dim searchString As String
Dim findPos As Integer
Try
searchString = TextBoxSearch.Text
findPos = InStr(txtClientArea.Text, searchString)
If findPos > 0 Then txtClientArea.Focus()
txtClientArea.SelectionStart = findPos - 1
txtClientArea.SelectionLength = searchString.Length
txtClientArea.ScrollToCaret()
Catch ex As Exception
MessageBox.Show(String.Concat("An error occurred: ", ex.Message))
End Try
End Sub
If you want your code work you need to pass the reference to the RichTextBox present in the first form to the findandReplace form.
Otherwise you will not be able to work with that instance of the RichTextBox.
Usually, this means that when you create and open an instance of the findandReplace form you pass the reference to the RichTextBox to work with in the call to the constructor. Something like this
Dim fReplace As frmFindandReplace = New frmFindandReplace(Me.txtClientArea)
fReplace.Show()
Here the New call reaches the constructor of frmfindandReplace. This call is usually hidden by VB.NET but you could add it writing explicit code for it
Public Class frmFindandReplace
Dim txtClientArea As RichTextBox
Public Sub New (ByVal txt as RichTextBox)
txtClientArea = txt
End Sub
Now the global variable txtClientArea inside the findandReplace class is assigned to the existing reference of the RichTextBox present in the first form and you could happily work with it
Protected Friend Sub findButton_Click(sender As Object, e As EventArgs) Handles findButton.Click
Dim a As String
a = TextBoxSearch.Text
Dim position = txtClientArea.Find(a, 0, RichTextBoxFinds.MatchCase)
.....
End Sub
And please make yourself a favor and start using the more complete methods available from the NET Framework library and stop using the old fashioned VBA methods.
For example the RichTextBox has a method that does exactly what you are trying to do in code. Find, search the content of the textbox and if it founds a match it highlight the text and return the starting position of the text.
There is no replace builtin method but having the position and the length is really simple to implement your own replacing code.
You Have defined b as a string. Change it to an integer. Also Instr doesn't allow you to set a start position, just a string to search and the string to search for and optionally the type of search - Binary or Text.
Finally rather than type If b then, use If b>0 then rather than turning off Option Strict. It's always better to write code with Option Strict on as it makes you write better code and in the long run is easier to chase down errors
I am trying to compare two strings that I know are equal to each other, but it is always skipping to the else. I've tried everything, .Equals, =, IsNot, they all don't work! The frustrating part is that I know the strings are equal! Please take a look at my code and see if it there is possible anything wrong with it.
Public Class Form1
Dim log As String
WithEvents xworker As New System.ComponentModel.BackgroundWorker
Private Sub Form1_Load(sender As Object, e As EventArgs) Handles MyBase.Load
xworker.RunWorkerAsync()
End Sub
Private Sub xWorker_DoWork(ByVal sender As Object, ByVal e As System.ComponentModel.DoWorkEventArgs) Handles xworker.DoWork
Dim qWorker = CType(sender, System.ComponentModel.BackgroundWorker)
Dim client As New Net.WebClient
log = client.DownloadString("http://########/log.txt")
End Sub
Private Sub xWorker_Completed(ByVal sender As Object, ByVal e As System.ComponentModel.RunWorkerCompletedEventArgs) Handles xworker.RunWorkerCompleted
If log.Equals(RichTextBox1.Text) Then
xworker.RunWorkerAsync()
Else
RichTextBox1.Text = log
xworker.RunWorkerAsync()
End If
End Sub
End Class
You needed to listen to #SLaks and #Hans Passant, they were right on the money.
I setup your code sample and it worked correctly if the source log.txt file didn't have a line terminator in it. Once I added the line terminator I got the results your are getting.
From the command window:
>? RichTextBox1.Text.Length
14
>? log.length
15
Using the QuickWatch window, and TABing until the Value field was selected:
Log result:
"log test 1234" & vbCrLf & ""
RichTextBox result:
"log test 1234" & vbLf & ""
The fix to the problem depends on what will actually get written to the log.txt file. I assume that "log test 1234" is just development code. If you are only interested in a single line as a result code then make sure you are not writing a line terminator. If your result codes are more complicated then you will need to do more parsing on the result than just an Equals compare.
Try this instead.
If log.ToLower().Trim() = RichTextBox1.Text.ToLower().Trim() Then
I think this is case sensitve compare. You should convert both of the strings to upper or to lower and then compare them
If Log.ToLower() = RichTextBox1.Text.ToLower() Then
Or you can use String.Compare method and set third param to true to ignore case
If String.Compare(log, RichTextBox1.Text, True) = 0 Then
I've read that the RichTextBox can change line endings when Text gets set. So the Text property might be returning a string that is different than what was set. I haven't been able to verify, but you can probably devise a quick test of this theory.
using VB.net and Visual studio is there a way to globally (across all fields in all forms in a project) prevent a user from entering a single quote character into a field. I'm thinking some sort of modification of the keypress event, but I'm not sure how to go about it. Currently I am currently using the ADDHANDLER, ADDRESSOF technique to assign this special code to a particular field, and I guess I could do a loop over all my contained controls on a particular form and assign the keypress code, but if there is a way to do it once without repeating the code on each form that would be great. Any hints graciously accepted. Thanks.
What about a regex? Stripping or converting to escape character on submit?
Would it be possible to pass an array where TextBox1 is TextBox1,Textbox2, etc. Obviously you would need to edit the expression if you only need to strip the single quote. This for all non alphabet characters. I don't do much with vb.net but thought this might be helpful.
Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged
StripNonAlphabetCharacters(TextBox1)
End Sub
Public Sub StripNonAlphabetCharacters(ByVal input As TextBox)
' pattern matches any character that is NOT A-Z (allows upper and lower case alphabets)
Dim rx As New Regex("[^a-zA-Z]")
If (rx.IsMatch(input.Text)) Then
Dim startPosition As Integer = input.SelectionStart - 1
input.Text = rx.Replace(input.Text, "")
input.SelectionStart = startPosition
End If
End Sub
The easiest solution is to create a derived TextBox and use that instead of the standard textbox.
Public Class NoQuoteTextBox
Inherits TextBox
Public Sub New()
AddHandler MyBase.KeyPress, AddressOf Handler
End Sub
Public Sub Handler(ByVal sender As Object, ByVal e As KeyPressEventArgs)
If e.KeyChar = "'" Then
e.Handled = True
End If
End Sub
End Class
Build your project then the NoQuoteTextBox (or whatever you decide to call it) will appear in the Toolbox in the Designer:
Use this new control instead of the standard textbox and it will handle the single quote for you.