WPF textbox to accept decimal numbers

Question

I want textbox to accept the decimal numbers like 123.45 or 0.45

I have added a code in PreviewtextInput event of textbox 

  foreach (char ch in e.Text)

                if (!Char.IsDigit(ch))

                    e.Handled = true;

But it allows only to accept the numbers and not decimals.

How I can allow the decimals numbers as it is a textbox of currency(amount).

 

Thanks

 

Answer 1

Why not do it in OnKeyDown?

And you can check KeyEventArgs.Key to see if you should handle the event.

    protected override void OnKeyDown(System.Windows.Input.KeyEventArgs aKeyEventArgs)

    {

      if (this._AllowedKeys.Count > 0)

      {

        aKeyEventArgs.Handled = !this._AllowedKeys.Contains(aKeyEventArgs.Key);

      }



      base.OnKeyDown(aKeyEventArgs);

    }

For decimals..

                this._AllowedKeys.Add(System.Windows.Input.Key.Decimal);

                this._AllowedKeys.Add(System.Windows.Input.Key.OemPeriod);

Answer 2

Hi,

  This behavior is perfectly correct because the dot - "." standing alone does not have any meaning as a digit.

following are valid digits: 1, 3.3, 23.124, 1., 23.0

Following are invalid digit: . -->(i meant dot), .12

so use the following code:

 

 

foreach (char ch in e.Text)

 

 

if (!(Char.IsDigit(ch) || ch.Equals('.')))

{

e.Handled =

 

true;

}

 

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- Jegan

Answer 3

Hi,

you could use Decimal.TryParse(e.text, testvar) for this kind of check...

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http://wpfglue.wordpress.com

Answer 4

HI

But how to restrict the number of decimal to one.

 

foreach (char ch in e.Text)

 

 

 

if (!(Char.IsDigit(ch) || ch.Equals('.')))

 

 

true;

}

As it allows more than one decimal i.e dot(.)

Thanks

{

e.Handled =

Answer 5

You may want to look into using RegularExpressions to validate your value.

http://msdn.microsoft.com/en-us/library/system.text.regularexpressions.regex%28VS.80%29.aspx

Answer 6

Hi Jegan,

Agree with Smith, Regular Expressions can make it easier.

Code snippets:

  private void TextBox_PreviewTextInput(object sender, TextCompositionEventArgs e)
  {
   Regex regex = new Regex("^[.][0-9]+$|^[0-9]*[.]{0,1}[0-9]*$");
   e.Handled = !regex.IsMatch((sender as TextBox).Text.Insert((sender as TextBox).SelectionStart,e.Text));
  }

 

Hope this helps.

Sincerely,

Bob Bao

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