Best method to restrict input

Best method to restrict input

• michael olson

  Can-Ann what is the status Did any of these work for you
  
  
  

• Darren Tao

  You can validate input in validating event

  with regex:

  Regex.IsMatch(<string>, "^\d{0,10}$") 'this match a string with 0-10 digits

  Regex.IsMatch(<string>, ^[a-zA-z]{0,2}$") 'this match a string with 0-2 chars beetween a and z case insensitive...

  
  

• Raguvind

  Good point Lepaca.

  I personally would try to avoid mixing 'N/A'

  with numbers. Perhaps a 'n/a' checkbox to

  the side.

  But, hey, what do I know

  
  
  

• Avi29

  I put this in a function which is called from the keypress event:

  int keyInt = (int)ch;

  if ((keyInt < 48 || keyInt > 57) && keyInt != 46 && keyInt != 8 && keyInt != 78 && keyInt != 65)

  {

  return false;

  }

  else

  {

  return true;

  }

  I seems to work OK but I do have to rely on the operators.

  Charles:

  I will take a look at Billy Hollis's validation controls: http://dotnetmasters.com/
  Thanks for the tip.

  
  

• quame

  Keypress event is not that great if you are

  going to allow 'na' also.

  Public Class Form1

  Private Sub TextBox1_Validating(ByVal sender As Object, _

  ByVal e As System.ComponentModel.CancelEventArgs) _

  Handles TextBox1.Validating

  ' Use the 'maxlength' suggestion also

  Dim chk As Boolean = IsNumeric(TextBox1.Text)

  If Not TextBox1.Text.ToUpper = "NA" And Not chk Then

  MsgBox("Must be numeric or 'NA'")

  TextBox1.Select()

  End If

  End Sub

  End Class

  
  
  

• Tom H.

  Change the property MaxLength on the Textbox to 10. Then use the validation in the previous post for the NA issue during validation.
  
  
  

• Just Phill

  I was kind of hoping I could check for these conditions in the keypress event.

  
  

• sdelmas

  Hi,

  I would suggest you use Billy Hollis's validation controls: http://dotnetmasters.com/
  These are windows forms controls that work on a concept similar than asp.net validation.

  For example once you drop the textbox validator on your form, for each textbox you can select which datatype if must contain (int, double, string, date, etc), the maximum length, whether it is required, min max values, regular expression or a custom validation method.

  Try it, you'll like it.

  Charles

  
  

• Maclau

  Can-Ann wrote:

  I was kind of hoping I could check for these conditions in the keypress event.

  You asked for the "best method"...  Now, I'm not saying this is the "best" but if you want your validation to occur on the KeyPress event, the following code will work well for you:

      Private Sub TextBox1_KeyPress(ByVal sender As Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TextBox1.KeyPress
          If Not Char.GetUnicodeCategory(e.KeyChar) = Globalization.UnicodeCategory.Control Then
              Dim testtxt As String
              testtxt = Me.TextBox1.Text.Insert(Me.TextBox1.SelectionStart, e.KeyChar)
              If Integer.TryParse(testtxt, Nothing) Then
                  If testtxt.Length > 10 Then
                      e.Handled = True
                  End If
              Else
                  Select Case testtxt
                      Case "N", "n", "NA", "na", "Na", "nA"
                      Case Else
                          e.Handled = True
                  End Select
              End If
          End If
      End Sub

  You'll need to set ShorcutsEnabled = False on the TextBox to avoid Paste issues.
  -EDIT- The Select statement could test the ToUpper() or ToLower() of "testtxt" and then you don't need as many cases, but the example allows any combination of the letters na.

  Hope that helps; good luck!

  
  
  

• Duncan Woods

  in this case, isnumeric isn't a good solution, because i.e.

  IsNumeric("12.3,") is true!

  in validating event, regex works better...

  
  

• Duckocide

  change the textlength to 10 and on the keypress event, check to see if the character pressed is numeric. if not, set e.Handled = true;

  private void TextBox1_keypress (object sender, KeyPressEventArgs e)

  {

     if (!Char.IsNumber(e.KeyChar) && !Char.Iscontrol(e.KeyChar))

     {

        e.Handled = true;

     }

  }

  
  
  
• Best method to restrict input