How to force textbox to take only numbers in WPF?

Question

I want user to enter only numeric values in TextBox.

I got this code:

private void txtType1_KeyPress(object sender, KeyPressEventArgs e)
{
     int isNumber = 0;
     e.Handled = !int.TryParse(e.KeyChar.ToString(), out isNumber);
}

But I am not getting textbox_KeyPress event and e.KeyChar while using WPF.

Whats the solution in WPF?

Edit:

I made a Solution!

private void txtName_PreviewTextInput(object sender, TextCompositionEventArgs e)
{
    CheckIsNumeric(e);
}

private void CheckIsNumeric(TextCompositionEventArgs e)
{
    int result;

    if(!(int.TryParse(e.Text, out result) || e.Text == "."))
    {
        e.Handled = true;
    }
}

Solution 1

protected override void OnPreviewTextInput(TextCompositionEventArgs e)
    {
        char c = Convert.ToChar(e.Text);
        if (Char.IsNumber(c))
            e.Handled = false;
        else
            e.Handled = true;

        base.OnPreviewTextInput(e);
    }

Solution 2

You can use a validation rule... http://www.codeproject.com/KB/WPF/wpfvalidation.aspx

Or make your own Maskable textbox http://rubenhak.com/?p=8

Solution 3

//Call this code on KeyDown Event
if((e.Key >= Key.NumPad0 && e.Key <= Key.NumPad9) || (e.Key == Key.Back))
{ e.Handled = false; }
else if((e.Key >= Key.D0 && e.Key <= Key.D9))
{ e.Handled = false; }
else
{ e.Handled = true; }

Solution 4

You can bind your textbox with a dependency property and inside dependency property's validation method you can check if int.tryparse returns true then fine otherwise you can go for default or you can reset value.

Or you can use WPF ValidationRules to find out when the value is changed. Once changed you can apply logic for inout validaiton.

Or you can use IDataError Info for validation.

Solution 5

bit enhanced version of Hasib Uz Zaman

     private void txtExpecedProfit_PreviewTextInput_1(object sender, TextCompositionEventArgs e)
    {
        CheckIsNumeric((TextBox)sender,e);
    }

    private void CheckIsNumeric(TextBox sender,TextCompositionEventArgs e)
    {
        decimal result;
        bool dot = sender.Text.IndexOf(".") < 0 && e.Text.Equals(".") && sender.Text.Length>0;
        if (!(Decimal.TryParse(e.Text, out result ) || dot )  )
        {
            e.Handled = true;
        }
    }

this will check for duplication .(decimal mark) and will not allow just only .(decimal mark)

View more solutions

Comments

[Falcon]

Got It Was Really Help full.. It worked....

[Pinotek]

View here You can find here a good overview of answers for it.

[Anna Lam]

Good answer! Although, I would replace all but the last line of your method body with e.Handled = !Char.IsNumber(Convert.ToChar(e.Text));

[Igor]

PreviewTextInput() will not catch the 'space' key press. Adding if (e.Key == Key.Space) e.Handled = true; in the PreviewKeyDown() would solve that problem.

[dcp]

This answer doesn't solve problem of user pasting a value into the textbox. The pasted value could contain letters.

[Dragos Stoica]

not working in conjunction to Shift. You can insert special characters

[סטנלי גרונן]

Better if you could add some explanation, dome details, not code only. The idea is that other users could also benefit from your answer as well (in the future), not only the OP. Just a thought :)