How can I accept the backspace key in the keypress event?

Question

This is my code:

private void txtAdd_KeyPress(object sender, KeyPressEventArgs e)
{
    if (!(char.IsLetter(e.KeyChar)) && !(char.IsNumber(e.KeyChar)         


        

Answer 1

I use the two following segments alot:

This one for restricting a textbox to integer only, but allowing control keys:

if (Char.IsDigit(e.KeyChar)) return;
if (Char.IsControl(e.KeyChar)) return;
e.Handled = true;

This one for restricing a textbox to doubles, allowing one '.' only, and allowing control keys:

if (Char.IsDigit(e.KeyChar)) return;
if (Char.IsControl(e.KeyChar)) return;
if ((e.KeyChar == '.') && ((sender as TextBox).Text.Contains('.') == false)) return;
if ((e.KeyChar == '.') && ((sender as TextBox).SelectionLength == (sender as TextBox).TextLength)) return;
e.Handled = true;

Answer 2

private void KeyPressNameSurname(object sender, KeyPressEventArgs e)
 {
     if (char.IsPunctuation(e.KeyChar) || char.IsSymbol(e.KeyChar) || char.IsDigit(e.KeyChar) )
     {
        e.Handled = true;
        myTextBox.Text = "Not Valid";
        myTextBox.Visible = true;
     }
     else
     {
        myTextBox.Visible = false;
     }
  }