Question

Im using VS2010, and I have a text box… I assign a KeyPress on the box, abd set the method like so:

private void MyButton_KeyPress(object sender, KeyPressEventArgs e)
    {
        e.Handled = true;
    }

I noticed that i am no longer able to enter any special keys such as the minus (-) and plus (+) sign into the textbox. Can someone please explain to me why i am no longer able to do this, and what i can do to fix this?

Ultimately I’m trying to only allow numeric keys to be entered, and i also want to allow the (-) minus sign, but if i cant get the minus sign in there, then i guess i wont be able to limit the text of the box

Answer 1

This should finish the job for you.

private void MyButton_KeyPress(object sender, KeyPressEventArgs e)
{
    if (e.KeyChar >= '0' && e.KeyChar <= '9') return;
    if (e.KeyChar == '+' || e.KeyChar == '-') return;
    e.Handled = true;
}

Here is how it works. If the character typed is one that you want, simply return from the function and let the normal handler take care of it. All other characters are marked as handled and so processing on them stops. Since nothing is done with them they are essentially thrown away. You could put everything in one if statement but I left it this way for clarity