I want to format my textbox in a way so that, user cant enter any symbol e.g () , . ; ' " £ $ % ^[]{}
If (Char.IsDigit(e.KeyChar) Or Char.IsControl(e.KeyChar) Or (e.KeyChar = ".")) Then
e.Handled = True
End if
This code will prevent user from entering digit or integer. But how can I prevent symbols?
Thanks in advance.
You can also use a "masked edit" from Ajax. The Ajax control toolkit can be found at:
http://www.asp.net/ajax/ajaxcontroltoolkit/Samples/MaskedEdit/MaskedEdit.aspx
Install Ajax. Follow the steps provided on the websites on how to add the AJAX controls to my Visual Studio. After that, drag the "MaskedEditExtender" Control to the textbox you want formatted.
In the properties field that says "Mask" I typed (999) 999-9999
After this I found out that I had to add something called "TollkitScriptManager" In design view, drag and drop the control above the txtbox which is the textbox you want the formatting done in. I do not think you have to change any of the properties to this and I believe that this control HAS to be above the textbox you want to format.
This may or may not be what you are looking for but it will allow a very specific format for a text box and force the user to only type in numbers or whatever you choose. This is very useful for formatting telephone numbers in the textbox.
I wrote a simple Class to do this in a previous question. Here is the VB.NET version of the code:
Public Class TextBoxFilter
<Flags()> Public Enum Filters
None = 0
Text = 1
Numbers = 2
AlphaNumeric = Filters.Text Or Filters.Numbers
Currency = 4
All = Filters.Text Or Filters.Numbers Or Filters.Currency
End Enum
Dim _keyFilter As Dictionary(Of TextBox, Filters)
Dim _allowedKeys As Dictionary(Of TextBox, String)
Dim _invalidKeys As Dictionary(Of TextBox, String)
Dim _keyEventArgs As Dictionary(Of TextBox, Windows.Forms.KeyEventArgs)
Private Shared DecimalMark As String = Application.CurrentCulture.NumberFormat.NumberDecimalSeparator
Private Shared NegativeMark As String = Application.CurrentCulture.NumberFormat.NegativeSign
Private Shared CurrencySymb As String = Application.CurrentCulture.NumberFormat.CurrencySymbol
Private Shared CurrencyDecimal As String = Application.CurrentCulture.NumberFormat.CurrencyDecimalSeparator
Public Sub New()
_keyFilter = New Dictionary(Of TextBox, Filters)
_allowedKeys = New Dictionary(Of TextBox, String)
_invalidKeys = New Dictionary(Of TextBox, String)
_keyEventArgs = New Dictionary(Of TextBox, KeyEventArgs)
End Sub
'set & remove filter'
Public Sub SetTextBoxFilter(ByVal textBox As TextBox, ByVal filter As Filters)
SetTextBoxFilter(textBox, filter, AllowedKeys(textBox), InvalidKeys(textBox))
End Sub
Public Sub SetTextBoxFilter(ByVal textBox As TextBox, ByVal allowedKeys As String)
SetTextBoxFilter(textBox, Filter(textBox), allowedKeys, InvalidKeys(textBox))
End Sub
Public Sub SetTextBoxFilter(ByVal textBox As TextBox, _
ByVal allowedKeys As String, ByVal invalidKeys As String)
SetTextBoxFilter(textBox, Filter(textBox), allowedKeys, invalidKeys)
End Sub
Public Sub SetTextBoxFilter(ByVal textBox As TextBox, ByVal filter As Filters, _
ByVal allowedKeys As String, ByVal invalidKeys As String)
If Not _keyFilter.ContainsKey(textBox) Then
'add the textbox and its filter if it does not exist in '
'the collection of registered textboxes '
_keyFilter.Add(textBox, filter)
_allowedKeys.Add(textBox, allowedKeys)
_invalidKeys.Add(textBox, invalidKeys)
_keyEventArgs.Add(textBox, New System.Windows.Forms.KeyEventArgs(Keys.None))
'add the event handlers '
AddHandler textBox.KeyDown, AddressOf KeyDownUp
AddHandler textBox.KeyUp, AddressOf KeyDownUp
AddHandler textBox.KeyPress, AddressOf KeyPress
AddHandler textBox.Validating, AddressOf Validating
AddHandler textBox.Disposed, AddressOf Disposed
Else
'change the filter of the textbox if it exists in '
'the collection of registered textboxes '
_keyFilter(textBox) = filter
_allowedKeys(textBox) = allowedKeys
_invalidKeys(textBox) = invalidKeys
End If
End Sub
Public Sub RemoveTextBoxFilter(ByVal textBox As TextBox)
If _keyFilter.ContainsKey(textBox) Then
_keyFilter.Remove(textBox)
_allowedKeys.Remove(textBox)
_invalidKeys.Remove(textBox)
_keyEventArgs.Remove(textBox)
RemoveHandler textBox.KeyDown, AddressOf KeyDownUp
RemoveHandler textBox.KeyUp, AddressOf KeyDownUp
RemoveHandler textBox.KeyPress, AddressOf KeyPress
RemoveHandler textBox.Validating, AddressOf Validating
RemoveHandler textBox.Disposed, AddressOf Disposed
End If
End Sub
Public Function ContainsTextBox(ByVal textBox As TextBox) As Boolean
Return _keyFilter.ContainsKey(textBox)
End Function
'properties'
Public Property Filter(ByVal textBox As TextBox) As Filters
Get
If ContainsTextBox(textBox) Then
Return _keyFilter.Item(textBox)
Else
Return Filters.None
End If
End Get
Set(ByVal value As Filters)
SetTextBoxFilter(textBox, value)
End Set
End Property
Public Property AllowedKeys(ByVal textBox As TextBox) As String
Get
If ContainsTextBox(textBox) Then
Return _allowedKeys(textBox)
Else
Return ""
End If
End Get
Set(ByVal value As String)
SetTextBoxFilter(textBox, Me.Filter(textBox), value, Me.InvalidKeys(textBox))
End Set
End Property
Public Property InvalidKeys(ByVal textBox As TextBox) As String
Get
If ContainsTextBox(textBox) Then
Return _invalidKeys(textBox)
Else
Return ""
End If
End Get
Set(ByVal value As String)
SetTextBoxFilter(textBox, Me.Filter(textBox), Me.AllowedKeys(textBox), value)
End Set
End Property
'event handlers'
Private Sub Disposed(ByVal sender As Object, ByVal e As System.EventArgs)
RemoveTextBoxFilter(DirectCast(sender, TextBox))
End Sub
Private Sub KeyDownUp(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyEventArgs)
'assign the modifiers'
_keyEventArgs(DirectCast(sender, TextBox)) = e
End Sub
Private Sub KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs)
'ensure key pressed is in the allowed keys'
Dim txt = DirectCast(sender, TextBox)
Dim c = e.KeyChar
Dim allowKey As Boolean = IsValidChar(txt, c, txt.SelectionStart)
'check for backspace & Ctrl combinations if the allowKey is still false'
If allowKey = False Then
If _keyEventArgs(txt).Control Then
'control modifier goes with A, X, C, V and Z for '
'Select All, Cut, Copy, Paste and Undo respectively'
Dim key = _keyEventArgs(txt).KeyCode
allowKey = (key = Keys.A OrElse key = Keys.X OrElse _
key = Keys.C OrElse key = Keys.V OrElse key = Keys.Z)
ElseIf _keyEventArgs(txt).KeyCode = Keys.Back Then
'allow the backspace key'
allowKey = True
End If
End If
'disable the key if it was not valid'
If Not allowKey Then
e.Handled = True
Beep()
End If
End Sub
Private Sub Validating(ByVal sender As Object, ByVal e As System.ComponentModel.CancelEventArgs)
Dim box = DirectCast(sender, TextBox)
Dim boxFlags = _keyFilter(box)
'skip validation if the textbox allows all entries or there is no text'
If boxFlags = Filters.All Or box.Text = "" Then Exit Sub
'otherwise check the characters entered'
Dim txtChars = box.Text.ToCharArray
Dim isValidEntry As Boolean = False
'check each caracter for an invalid entry'
For i = 0 To txtChars.Length - 1
Dim c = txtChars(i)
isValidEntry = IsValidChar(box, txtChars(i), i)
If Not isValidEntry Then
box.Select(i, 1)
Exit For
End If
Next
If Not isValidEntry Then e.Cancel = True
If Not isValidEntry Then
MsgBox("The text entered is invalid for the format " & boxFlags.ToString & "." & _
If(_allowedKeys(box) <> "", vbCrLf & "Additional Allowed Keys: " & _allowedKeys(box), "") & _
If(_invalidKeys(box) <> "", vbCrLf & "Additional Invalid Keys: " & _invalidKeys(box), ""), _
MsgBoxStyle.Critical, "Invalid Entry")
End If
End Sub
Private Function IsValidChar(ByVal textBox As TextBox, ByVal c As Char, ByVal charIndex As Integer) As Boolean
'ensure key pressed is in the allowed keys '
Dim pF = _keyFilter(textBox)
Dim aK = _allowedKeys(textBox)
Dim iK = _invalidKeys(textBox)
Dim shouldAllow As Boolean = False
'if filter is set to all, return true unconditionally '
If pF = Filters.All Then Return True
'check preset filters '
'check for text '
If EnumHasFlag(pF, Filters.Text) Then
If Not Char.IsDigit(c) Then
shouldAllow = True
Else
'if the character is a digit, check for the number flag (AlphaNumerics) '
If EnumHasFlag(pF, Filters.Numbers) Then
shouldAllow = True
End If
End If
End If
'check for numbers '
If shouldAllow = False AndAlso EnumHasFlag(pF, Filters.Numbers) Then
If Char.IsDigit(c) Then
shouldAllow = True
ElseIf DecimalMark.Contains(c) Then
'allow the decimal if there is no decimal in the textbox's
'text or the selected text contains the mark'
If Not textBox.Text.Contains(c) OrElse textBox.SelectedText.Contains(c) Then
shouldAllow = True
End If
ElseIf NegativeMark.Contains(c) AndAlso _
(charindex <= NegativeMark.IndexOf(c)) Then
'allow the negative mark if we are at the start of the'
'textbox'
shouldAllow = True
End If
End If
'check for currency '
If shouldAllow = False AndAlso EnumHasFlag(pF, Filters.Currency) Then
If Char.IsDigit(c) Then
shouldAllow = True
ElseIf CurrencyDecimal.Contains(c) Then
'allow the currency decimal mark if it does not exist in the '
'textbox''s text or the selected text contains the mark '
If Not textBox.Text.Substring(0, charIndex).Contains(c) OrElse _
textBox.SelectedText.Contains(c) Then
shouldAllow = True
End If
ElseIf CurrencySymb.Contains(c) AndAlso _
(charIndex <= CurrencySymb.IndexOf(c)) Then
'allow the currency symbol if we are in a valid position'
shouldAllow = True
End If
End If
'now check for extra allowed keys'
If Not shouldAllow Then
shouldAllow = aK.Contains(c)
End If
'and then check for extra invalid keys'
If shouldAllow AndAlso iK.Contains(c) Then
shouldAllow = False
End If
Return shouldAllow
End Function
<System.Diagnostics.DebuggerStepThrough()> _
Private Function EnumHasFlag(ByVal value As [Enum], ByVal flag As [Enum]) As Boolean
Return (Convert.ToInt64(value) And Convert.ToInt64(flag)) = Convert.ToInt64(flag)
End Function
End Class
Just place this class in your project and use it in your form as follows
Public Class Form1
Dim filter = New TextBoxFilter()
Private Sub Form1_Load(object sender, System.EventArgs e) Handles MyBase.Load
filter.SetTextBoxFilter(TextBox1, TextBoxFilter.Filters.Numbers)
End Sub
End Class
U can use use pattern attributes like this
txtTel.Attributes.Add("placeholder", FormatTel.Libelle)
txtTel.Attributes.Add("title", FormatTel.Libelle)
txtTel.Attributes.Add("pattern", FormatTel.ExprReg)
I suggest using regex (regular expressions). What you have to do is checking each and every single character that the user enters. If the characters are invalid you have to replace them with valid characters. The regular expression pattern "[^!@%&$#()*^\0-9.+-=][_]" matches alphabetic characters and spaces. Symbol ^ in the above pattern means not matching with any of the following characters. Symbol \ is a scape character and [] denotes a matching range of characters. If the string matches the above pattern you have to replace the character that the user has entered with a valid character.
In the following code, the user input is checked for invalid characters every time he/she enters a new character.
For the code to work you must import the following namespace:
Imports System.Text.RegularExpressions
The complete code for the windows form is here:
Imports System.Text.RegularExpressions
Public Class RegexTest
Private Sub TextBox1_TextChanged(sender As Object, e As EventArgs) Handles TextBox1.TextChanged
Dim theText As String = Me.TextBox1.Text
Dim cursor1 As Integer = Me.TextBox1.SelectionStart
Dim cursor2 As Integer = cursor1
Dim finalText As String = ""
If theText IsNot Nothing AndAlso theText.Length >= 1 Then
For x As Integer = 0 To theText.Length - 1 Step +1
Dim Letter As String = theText.Substring(x, 1)
Dim extStr As String = ExtractFirstString(Letter, "[^!@%&\$#\(\)\*\^\\0-9\.\+\-=\]\[_]")
If extStr <> Letter Then
extStr = ""
finalText &= extStr
Else
finalText &= Letter
End If
Next
End If
If finalText <> theText Then
Me.TextBox1.Text = finalText
Me.TextBox1.SelectionStart = cursor2
End If
End Sub
Private Function ExtractFirstString(ByVal sourceStr As String, ByVal pattern As String) As System.String
Dim mc As System.Text.RegularExpressions.MatchCollection
Dim result As String = Nothing
Dim i As Integer
Dim brk As Boolean = False
If sourceStr IsNot Nothing Then
' match email addresses!
mc = Regex.Matches(sourceStr, pattern)
If mc IsNot Nothing Then
Dim results(mc.Count - 1) As String
For i = 0 To results.Length - 1 Step +1
result = mc(i).Value
brk = True
Return result
Exit For 'only return the first match
Next
End If
End If
Return Nothing
End Function
End Class
You have to create a textbox named TextBox1 on the form and handle its TextChanged evnet.
