Textbox validation for alphabetical and alphanumeric textbox with "." - vb.net

Question

This is what i am using but i want to include "." dot also as an input in the textbox
If Char.IsLetter(e.KeyChar) = False Then
If e.KeyChar = CChar(ChrW(Keys.Back)) or e.KeyChar = CChar(ChrW(Keys.Space)) Then
e.Handled = False
Else
e.Handled = True
End If
End If
and
If Char.IsLetterOrDigit(e.KeyChar) = False Then
If e.KeyChar = CChar(ChrW(Keys.Back)) or e.KeyChar = CChar(ChrW(Keys.Space)) Then
e.Handled = False
Else
e.Handled = True
End If
End If

Answer 1

To include a period in the list of valid characters, use an OrElse term to test for multiple conditions. Note that "." is a String, different to "."c which is a Char.
If Not (Char.IsLetterOrDigit(e.KeyChar) OrElse e.KeyChar = "."c) Then
If e.KeyChar = CChar(ChrW(Keys.Back)) or e.KeyChar = CChar(ChrW(Keys.Space)) Then
e.Handled = False
Else
e.Handled = True
End If
End If

Answer 2

You could just use ASCII code
If Asc(C$(F1)) > 122 Or Asc(C$(F1)) < 97 And Asc(C$(F1)) > 90 Or Asc(C$(F1)) < 65 And Asc(C$(F1)) > 57 Or Asc(C$(F1)) < 48 Then
Label9.Text = C$(F1) + " is an invalid Charater!"
End If
For a single character you can just do Or variable =".". ASCII works when you want a range.
The code snippet is from Numeric Base conversion program check for invalid charters in a number, which will convert any base from 2 to 36. And, with minor tweaking will work in any form of BASIC including Applesoft (tweak no end if, and all on one line, label9.text becomes a text varible) which can also be done in VB.

Answer 3

You can use my control:
''' <summary>
''' By Amen Ayach
''' Use RoundNumber property to set how many decimal after "."
''' example: RoundNumber = 3 so if you write 654.4444 so onlostFocus you'll see 654.444
''' </summary>
''' <remarks></remarks>
Public Class TBRound
Inherits TextBox
Dim Enterly As Boolean = True
Private _RoundNumber As Integer = 0
Public Property RoundNumber() As Integer
Get
Return _RoundNumber
End Get
Set(ByVal value As Integer)
_RoundNumber = value
End Set
End Property
Public Overrides Property Text() As String
Get
Return MyBase.Text
End Get
Set(ByVal value As String)
MyBase.Text = value
End Set
End Property
Public Function format_Number(ByVal nb As String, ByVal isDivided As Boolean, ByVal NumberAfterComma As Integer) As String
Dim str As String = ""
Try
Dim fromatString As String = ""
Dim nbs As String = "."
For i As Integer = 0 To NumberAfterComma - 1
nbs += "0"
Next
If isDivided Then
str = "#,###"
Else
str = "#"
End If
str += nbs
str = Format(Val(Decimal.Parse(nb.ToString())), str)
Catch
End Try
Return str
End Function
Private Sub TBRound_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles Me.KeyPress
Dim allow As String = "0123456789." + ChrW(Keys.Back) + ChrW(Keys.Delete)
If Not allow.Contains(e.KeyChar) Then
e.Handled = True
End If
End Sub
Private Sub TBRound_LostFocus(ByVal sender As Object, ByVal e As System.EventArgs) Handles Me.LostFocus, Me.Validated
Try
If Not Decimal.TryParse(MyBase.Text, New Decimal) Then
MyBase.Text = "0"
Else
ValDateMe()
End If
Catch
End Try
End Sub
Private Sub ValDateMe()
Try
Dim value = MyBase.Text
If Decimal.TryParse(MyBase.Text, New Decimal) Then
If MyBase.Text <> format_Number(MyBase.Text, False, RoundNumber) Then
MyBase.Text = format_Number(MyBase.Text, False, RoundNumber)
End If
Else
Enterly = False
MyBase.Text = "0"
Enterly = True
End If
Catch
End Try
End Sub
End Class

Answer 4

You can use the following function:
Private Function StripInput(sender As String) As String
If sender <> String.Empty Then
Dim lastChr As String = sender(sender.Length - 1)
Dim stripList As String = "`¬!""£$%^&*()_+-=}{[]}~##'':?/>.<,|\;"
If stripList.Contains(lastChr) Then
Return sender.Substring(0, sender.Length - 1)
Else
Return sender
End If
Else
Return sender
End If
End Function
and call it from the TextChanged handler of the text box with :
sender.text = StripInput(sender.text)
sender.SelectionStart = sender.Text.Length + 1
And if you want to include any character, simply remove it from the strip list.