I'm creating a form with three text boxes with a 'subtotal', 'amount tendered' and 'change' box. Both subtotal and change boxes are disabled which means the user can only input numbers in the tendered box. I'm using the following code which I found from http://www.vbdotnetheaven.com/blogs/5908/restricting-user-input-in-vb-net.aspx to limit the input:
Private Sub TextBox1_KeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress
If Not Char.IsDigit(e.KeyChar) Then
e.Handled = True
End If
End Sub
My concern is that that specific coding works for limiting the input of numbers, but it also disabled the backspace, dot and delete key. I'm fairly new to this (we only started discussing things about VB/Studio less than two weeks ago, I have no prior experience about using Keypresses but I wanted to try)
I've tried manipulating the if statement (and also adding if statements) by excluding the spacebar's ASCII value, only to end up with a warning about incompatible types. I can replace text by double clicking the text input when the form is running, but my app will most likely be utilizing the keyboard mainly because it is a transaction app, so the backspace and more importantly the dot is really needed. How do I exclude both from being disabled?
Take a look at the sample for Control.KeyDown in the MSDN documentation, it's about 95% of what you want.
That said, be aware, there's more work to do. What happens if someone enters 124.34.22? You might consider a MaskedTextBox, but if this is an exercise for learning Visual Basic, that's pretty much cheating :)
Related
I want my Richtextbox to be always at the bottom and "autoscroll" to the end.
I found this with some google searches:
Private Sub RichTextBox1_TextChanged(sender As Object, e As EventArgs) Handles RichTextBox1.TextChanged
RichTextBox1.SelectionStart = RichTextBox1.TextLength
RichTextBox1.ScrollToCaret()
End Sub
This seems to work but as the text updates it jumps to the top of the box and with another update to the bottom. Can someone help me out? Or is there a better method to keep the Textbox at the end?
Thanks,
Max
Your code kind of works- What I would suggest to solve your initial problem is to alter your code slightly and add
RichTextBox1.SuspendLayout()
at the beginning of your sub, and
RichTextBox1.ResumeLayout()
at the end.
However, if your cursor isn't on the last line and you type something, the character will appear at the cursor before moving to the end of the text. I'm guessing you don't want that behaviour - In which case you should add the code into a KeyPress event.
There are several possible behaviours. Do you want to be able to type anywhere, or only at the end of the text? Or just to place the cursor at the end under certain circumstances - for example when the RichTextBox is first populated with a bunch of text? Or maybe something else.
The simplest solution would be for the user just to press the keys Ctrl-End. That doesnt need any code at all.
I have a form with a status strip, which contains a progress bar an a label. Both of these are used to show the user the status/progress of several background workers.
My problem is that sometimes the label is longer than the form is wide (it contains Parameter names that vary quite widely in length). The form has a constant width and is not re-sizable by the user. When this issue occurs the label just appears as blank, I would instead like to cut the label to the length of the form and concatenate "..." on the end.
Can anyone give me some advise on where to start with this? i have tried Google and SO searches and have been unable to come up with anything similar. I essentially need to find the length of the string as it will display on the form, but I don't know where to start with that.
First thing to do is to change the StatusStrip.LayoutStyle from Table to Flow. Which will prevent the label from disappearing. Next, you still want the user to have a chance to read the full text of the label even though it is truncated. Set the StatusStrip.ShowItemToolTips property to True and the label's AutoToolTip to True.
Getting the label's text to not overlap the grip is an uglier problem to fix but one you don't have since you made your form un-resizable. Set the form's SizeGripStyle property to Hide.
This will fix your problem, no code required.
You can try something like this:
Private Sub Label1_Click(sender As Object, e As EventArgs) Handles Label1.Click
If Label1.Text.Length > iMaxLblLenght Then
Label1.Text = Label1.Text.Substring(0, iMaxLblLenght) & "..."
End If
End Sub
So I have a form with a variety of different controls (combobox, textboxes, listboxes, etc).
My first thought is to create a If, Else, End If statement. Well while that would work, it could also get pretty long, depending on the amount of controls and combinations.
Validation could include if a listbox is filled, checkbox is checked, etc pertaining to WinForms.
Is there a better solution to check all possiblities than an If statement?
It might be worthwhile to do the error checking as the user fills out the form. This could be implemented with the LostFocus event. Ex:
Private Sub btnTest_Leave(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles yourbutton.LostFocus
Dim txt = yourbutton.Text
If txt = "yourtest" Then
'do stuff
EndIf
End Sub
As above. It depends on the Validation you are trying to do. Are you validating user input, datatype lenght range, etc. Are you validating business rules. Should such and such a value equal something else. There's all kinds of possibilities.
I have a program that replaces every letter of the alphabet with something new inside the same textbox by clicking a button then buy clicking the button it translates it back to original text.
However when i run this program, yes it does work as needed but not 100%
Because after i click the button to translate, (yes it shows translated)
If delete the translated text and type something new, it goes back to the old text.
(this does not happen if i click the button again, it shows the orignal text. But if i type something new it will translate it.)
Any suggestions?
This is a continuation of your other question. You will need to reset your Boolean variable when you type in your TextBox i.e.
Private Sub TextBox1_KeyPress(sender As Object, e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress
bConverted = False
End Sub
How can I refer to the control while I am inside a control's method in VB.NET?
For example, I want in a textbox to show a message box with that textbox's text every time the text changes. The code would be something like:
Private Sub TextBox1_TextChanged(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles TextBox1.TextChanged
msgbox("The text is:"+ Me.text)
' ok the line above wont work i already know that, because "Me" refer to the form,
' not the control textbox1
' how i will refer to the textbox1's text???
' i dont want to use "textbox1.text" is there a way similar like the "Me" is for forms?
' because i want to copy-paste a code like this in a lot of controls and do not want to
' have to change in every copy the name to each control name
End Sub
I hope I made myself clear; my English needs some improvement :D
No, there's no keyword that allows you to do that. However, every event raised by a control passes in a sender parameter that you can use to determine which particular control raised that event.
Note that this parameter is always typed as a basic Object (because it can represent any possible control), so you'll need to downcast to a more specific control class if you need to access any of the unique members that it exposes. Since you're handling an event raised by a TextBox control, you know that the sender must be of type TextBox, so you can simply use DirectCast to handle the upcasting. You don't have to worry that an InvalidCastException will be thrown.
For instance, your above example would become:
Private Sub TextBox1_TextChanged(ByVal sender As Object, ByVal e As EventArgs) Handles TextBox1.TextChanged
Dim textBox As TextBox = DirectCast(sender, TextBox)
MessageBox.Show("The text is: " & textBox.Text)
End Sub
That being said, there are a couple of concerning things that jump out at me in your question:
Any time that your approach to solving a problem is "copy-pasting" code, you should stop, take a step back, and try to figure out if there's any better way to achieve your ultimate goal.
For example, if you need every textbox on your form to react in the same way whenever a particular event is raised, you should consider subclassing the existing TextBox control and consolidating all of your code in one place. Remember that you can inherit off of most of the standard controls to add custom functionality. This is often a far better solution than copying and pasting code to multiple places in your project. If you ever need to track down a bug or modify that functionality, you'll only have to change it one place in your code, rather than several. As a somewhat cheekier benefit, you'll be able to use Me to refer to that control when you're editing its subclass.
You should always prefer to concatenate (combine) strings using the & operator in VB.NET, rather than the + sign. Or perhaps even better, the String.Concat or String.Format methods.
There is no reason to use MsgBox in VB.NET, as opposed to MessageBox.Show. No, this won't improve performance of your application, but it's a good practice to get into for .NET languages.
The sender variable contains the TextBox instance you want to access. You only need to convert the sender to TextBox.