Format text box to accept only numbers and white spaces and plus sign

Question

I am trying to make a text-box which will only accept numbers, white spaces and plus sign.

Currently I have done something like this in KeyPressEvent of the textbox

if (!char.IsDigit(e.KeyChar) && !char.IsControl(e.KeyChar) &&!char.IsWhiteSpace(e.KeyChar))
    {
                e.Handled = true;
    }

I want to accept the + sign as well

Update

I did handle the !char.IsSymbol(e.KeyChar) but it will accept the = sign as well with the +

Any help!!!

Thanks

Answer 1

For having "during input" control and validating control, you can make something like that.

But you'll have many things in your textbox (1+++ +2 34+), which doesn't mean a lot...

textBox.KeyDown += (sender, e) =>
                               {
                                   if (!(
                                       //"+
                                       e.KeyCode == Keys.Add || 
                                       //numeric
                                       (e.KeyCode >= Keys.NumPad0 && e.KeyCode <= Keys.NumPad9) || 
                                       //space
                                       e.KeyCode == Keys.Space))
                                   {
                                       e.Handled = true;
                                   }
                               };
textBox.Validating += (sender, eventArgs) =>
                                  {
                                      var regex = new Regex(@"[^0-9\+ ]+");
                                      textBox.Text = regex.Replace(textBox.Text, string.Empty);
                                  };

Answer 2

Strictly speaking you could append

     && !e.KeyChar == '+' 

to your criteria and it should work as far as keyboard input is concerned , but if the goal is to only allow numeric input the .net control library also contains a NumericUpDown control that can do the trick.

Answer 3

Added

var reg = new Regex(@"^\\+?(\\d[\\d-. ]+)?(\\([\\d-. ]+\\))?[\\d-. ]+\\d$");

as regex

Answer 4

This works fine for me:

if (!(char.IsLetter(e.KeyChar) && (!char.IsControl(e.KeyChar) 
    && !char.IsDigit(e.KeyChar) && !(e.KeyChar == '.'))
{
    e.Handled = true;
}

I added the char.IsControl because it allows you to use Backspace in a typeerror case.