Allowing Only 1 Decimal "." in Textbox

Question

I am having trouble making it where if the user types more than one "." decimal they get a error msg or whatever. Mainly having problems coding the Character "."
             Thanks

Answer 1

I don't know what you mean by coding the character '.' ? A maskededitbox is the easiest solution to your problem.

 

Answer 2

Well what I'm trying to do is make it where you cant put 2.2.2 and only allow the one decimal 2.2 Dont know if maskedtextbox will do that?

Answer 3

Yes, that is precisely what it is for.

 

Answer 4

I geuss I should say how do you limit a maskedtextbox to only accept 1 decimal?
    Thank for help so far..

Answer 5

I don't know, I prefer to write my own code to control this sort of thing, but I've learned it's easier to point people to the built in control. 

I'm just using google to bring up the MaskedTextBox docs on MSDN.

http://windowssdk.msdn.microsoft.com/en-us/library/kkx4h3az.aspx

Looks like the Mask property is what you want, I'd guess that "0000.00" allows up to four digits before and two after the only decimal point in the number. 

Answer 6

Nah,    FormatNumber ("textbox1, 4)  4 being the amount of zeros need to find out how to code a period into the code but dont know how to refer to period key in Vb2005

Answer 7

The period key is just that, a period,  "." - what's wrong with that ?

 

Answer 8

I just created a VB.NET project, added a MaskedTextBox, set the mask to 0000.00 in the designer, ran it, and it works great.  It actually stops you from typing the ., it provides it.

The alternative is to handle the KeyPress event of a normal text box and do something like this :

private void OnNumericKeyPress(object sender, KeyPressEventArgs e)

{

if (Char.IsNumber(e.KeyChar) || e.KeyChar == '.')

{

TextBox tb = sender as TextBox;

int cursorPosLeft = tb.SelectionStart;

int cursorPosRight = tb.SelectionStart + tb.SelectionLength;

string result = tb.Text.Substring(0, cursorPosLeft) + e.KeyChar + tb.Text.Substring(cursorPosRight);

string[] parts = result.Split('.');

if (parts.Length > 1)

{

if (parts[1].Length > 2 || parts.Length > 2)

{

e.Handled = true;

}

}

}

else

{

e.Handled = !Char.IsControl(e.KeyChar);

}

}

I've provided the C# code in case the VB.NET code converter I use doesn't emit code that works, but according to that, the VB code is :

   Private  Sub OnNumericKeyPress(ByVal sender As Object, ByVal e As KeyPressEventArgs)
            If Char.IsNumber(e.KeyChar) Or e.KeyChar = "."c Then
                Dim tb As TextBox =  sender as TextBox
 
                Dim cursorPosLeft As Integer =  tb.SelectionStart
                Dim cursorPosRight As Integer =  tb.SelectionStart + tb.SelectionLength
 
                Dim result As String =  tb.Text.Substring(0,cursorPosLeft) + e.KeyChar + tb.Text.Substring(cursorPosRight)
 
                Dim parts() As String =  result.Split("."c) 
 
                If parts.Length > 1 Then
                    If parts(1).Length > 2 Or parts.Length > 2 Then
                        e.Handled = True
                    End If
                End If
            Else
                e.Handled = Not Char.IsControl(e.KeyChar)
            End If
        End Sub

'----------------------------------------------------------------
' Converted from C# to VB .NET using CSharpToVBConverter(1.2).
' Developed by: Kamal Patel (http://www.KamalPatel.net)
'----------------------------------------------------------------

Now you see why I recommend the MaskedTextBox :-)

Answer 9

hmm if (input.text.Contains("."))
{
    e.Handled = true; ???
}

---

Daniel K Ward

Answer 10

 

1	Private Sub ntb_TextChanged(ByVal sender As Object, ByVal e As System.EventArgs) Handles ntb.TextChanged
2	If Me.Check Then
3	Dim txt$ = Me.ntb.Text
4	If txt = Nothing Then
5
6	ElseIf txt.Length = 0 Then
7
8	ElseIf txt = "0" Then
9
10	ElseIf txt.EndsWith(",") Or txt.EndsWith(".") And lString.Recognize.isStrictInt(lString.Missing.remlchr(txt)) Then
11
12	ElseIf (lString.c.CountForeigners(txt, lString.constants.numbers) > 1) Then
13	Dim bkp As New Support.cTextBox.TextSelection(Me.ntb)
14	If lString.Recognize.isDouble(txt) Then
15	Dim val# = lString.Easy.toDouble(txt)
16	Me.ntb.Text = val.ToString
17	bkp.TryApply(Me.ntb)
18	Else
19	Me.ntb.Text = ""
20	End If
21	ElseIf ((Strings.InStr(txt, ".") > 0) Or Strings.InStr(txt, ",") > 0) And txt.EndsWith("0") Then
22
23	Else
24	Dim bkp As New cTextBox.TextSelection(Me.ntb)
25	Dim val# = lString.Easy.toDouble(txt)
26	Me.ntb.Text = val.ToString
27	bkp.TryApply(Me.ntb)
28	End If
29	End If
30	End Sub

Annotations:
#2: Check says that autocorrection of textbox is enabled
#10: IsStrictInt determines string to or not to consist of only numbers
#10: remlchr removes last char in hope it can be dot or comma
#12: c.CountForeigners returns count of nonumeric characters in string if used with "012..89" const
#13: Class TextSelection provides mechanism to storing selectionStart and selectionLength and recover it or supply some intelligent behaviour if recovery is not possible
#14: IsDouble Checks string against all possible formats of double string representation (dots, commas, E+)
#15: ToDouble uses same mechanism as IsDouble to parse string to double, possibly synonym, maybe extension to Double.Parse
#17: recovering maximum of cursor and selection information destroyed by hard assignation of text value

You can find this as part of my Support library, namely Support.cTextBox.DoubleBox, which is so called control behaviour extension class, which instantiated for some control modifies its behaviour and optionally provides Value# property. Support is and will be free and open source. You can ispire what is to be done if you want to do it yourself, from this code, or you can simply try to use my DLL. But DLL is about 2 megs, having lot of different stuff inside...Anyway I wouldn't support you to use whole support.dll, for it contains thousands of functions which are not fully annotated. And few which are not debugged at all. You can also extract only DoubleBox with related functions from it :)

Answer 11

My C# contribution is : Only one decimal separator in the textbox + controlled number of decimal digits,

-------------------------

using System.Globalization;

...

private void textBox_KeyPress(object sender, KeyPressEventArgs e)

 

        {

             CultureInfo ci = System.Globalization.CultureInfo.CurrentUICulture;

            char cDecimalSeparator = ci.NumberFormat.CurrencyDecimalSeparator[0]; // "." or "," depending of systems config.

            bool bDecimalSeparatorFound = (0 <= this.textBox.Text.IndexOf(cDecimalSeparator ));

 

            if ( (!char.IsControl(e.KeyChar) && !char.IsDigit(e.KeyChar) && !(e.KeyChar==cDecimalSeparator ))

                || (e.KeyChar == cDecimalSeparator && bDecimalSeparatorFound )) // only one decimal separator

            {

                // unauthorized KeyChar or double decimal separator received : skipping this one

                e.Handled = true;

            }

 

            // only "ci.NumberFormat.CurrencyDecimalDigits" numbers allowed after decimal separator

            if (char.IsDigit(e.KeyChar) && bDecimalSeparatorFound )

            {

                int nDecimalDigits = this.textBoxAmount.Text.Length 

                    - this.textBox.Text.LastIndexOf(ci.NumberFormat.CurrencyDecimalSeparator) - 1;

 

                if (nDecimalDigits >= ci.NumberFormat.CurrencyDecimalDigits)

                    e.Handled = true; // doesn't comply to system configuration : skipping this one

            }

    

           // Everything seems okay, let base class handle this one!

            base.OnKeyPress(e);

        }

 

 

 

Hope this helps :)