Allow only 2 Decimal points

In window textbox, I'd like to just allow 2 decimal points only. I could set text box only numeric but don't know how to limit 开发者_StackOverflow中文版2 decimal points.

For example, 743.56

My code is below

  Private Sub txtPrice_KeyPress(sender As Object, e As KeyPressEventArgs) Handles txtPrice.KeyPress        
    'allow numeric 
    If Not Char.IsControl(e.KeyChar) AndAlso Not Char.IsDigit(e.KeyChar) AndAlso e.KeyChar <> "."c Then
        e.Handled = True
    End If

    ' only allow one decimal point
    If e.KeyChar = "."c AndAlso TryCast(sender, TextBox).Text.IndexOf("."c) > -1 Then
        e.Handled = True
    End If

   End Sub

How to?

Try using a NumericUpDown rather than a TextBox. A NumericUpDown lets you specify the number of decimal places to go to, as well as automatically limiting it to numbers. You also have two handy little up and down buttons.

A simpler solution would be to just use:

txtPrice.Text = String.Format("{0:n2}", numberVariableHere);

Here is the code, I have tested, I am just giving permission to user to enter only one digit after decimal point; you can change the value 2 to up to your choice.

Private Sub tb_KeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles tb.KeyPress
    If Not Char.IsDigit(e.KeyChar) And Not e.KeyChar = "." Then
        e.Handled = True
    Else
        If e.KeyChar = "." And tb.Text.IndexOf(".") <> -1 Then
            e.Handled = True
        ElseIf e.KeyChar = "." Then
            e.Handled = False
        ElseIf Char.IsDigit(e.KeyChar) Then
            If tb.Text.IndexOf(".") <> -1 Then
                If tb.Text.Length >= tb.Text.IndexOf(".") + 2 Then  'replace 2 for greater numbers after decimal point
                    e.Handled = True
                End If
            End If
        End If
    End If
End Sub

I have tested this code for up-to 2,3,4 decimal points

Now it works. Please check my code below

        '2 decimal points only
    'If key-in is after decimal point
    If txtPrice.SelectionStart > txtPrice.Text.IndexOf(Chr(46)) Then
        'If text not select All
        If txtPrice.SelectedText.Length = 0 Then
            If (txtPrice.Text.Trim() <> "") Then
                If (rexPrice.IsMatch(txtPrice.Text) = False) AndAlso e.KeyChar <> ControlChars.Back Then
                    e.Handled = True
                End If
            End If
        End If
    End If

Try this code (It will allow only numbers with a decimal point):

Private Sub txtCostPrice_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles txtCostPrice.KeyPress
    If InStr(txtCostPrice.Text, ".") And e.KeyChar = "." Then e.Handled = True
    If Char.IsDigit(e.KeyChar) = False And Char.IsControl(e.KeyChar) = False Then
        If e.KeyChar <> "." Then e.Handled = True
    End If
End Sub

i think this code help you to solve your problem

dim n as integer 
n=0
 Private Sub TextBox1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress
        If e.KeyChar = Chr(46) Then
            n = Len(TextBox1.Text)
        End If
        If Len(TextBox1.Text) >= n + 2 And n <> 0 Then
            TextBox1.Enabled = False
        End If
    End Sub

Private Sub txtVatRate_KeyPress(sender As Object, e As System.Windows.Forms.KeyPressEventArgs) Handles txtVatRate.KeyPress
    OnlyAllowPostiveNumbers(sender, e, 1)
End Sub

Public Function OnlyAllowPostiveNumbers(sender As Object, e As System.Windows.Forms.KeyPressEventArgs, Optional ByRef iDeimalPlaces As Integer = 0) As System.Windows.Forms.KeyPressEventArgs
    'Only allow numeric values with the exception of spaces ie '07969 860053' and backspace
    If (Microsoft.VisualBasic.Asc(e.KeyChar) < 48) Or (Microsoft.VisualBasic.Asc(e.KeyChar) > 57) Then
        e.Handled = True
    End If
    'Backspace
    If (Microsoft.VisualBasic.Asc(e.KeyChar) = 8) Then
        e.Handled = False
    End If
    If (Microsoft.VisualBasic.Asc(e.KeyChar) = 46) And InStr(sender.text, ".") < 1 Then
        e.Handled = False
    End If
    If (Microsoft.VisualBasic.Asc(e.KeyChar) > 48) And (Microsoft.VisualBasic.Asc(e.KeyChar) < 57) Then
        If InStr(sender.text, ".") > 0 Then
            Dim n As Integer = InStr(sender.text, ".")
            If n <= (sender.text.length - iDeimalPlaces) Then
                e.Handled = True
            End If
        End If
    End If
    Return e
End Function