Allow backspace button to work in validated TextBox

Question

I have the following code to only allow letters in the text box:

private void TextBox1_KeyPress(object sender, KeyPressEventArgs e)
{
  Char pressedKey = e.KeyChar;
  if (Char.IsLetter(pressedKey))
 {
// Allow input.
e.Handled = false
}
  else
e.Handled = true;
}
}

How can I allow the backspace key to work because, it doesnt let me to delete characters after typed

does this help? http://stackoverflow.com/questions/1191698/how-can-i-accept-the-backspace-key-in-the-keypress-event — bas, Mar 10 '13 at 20:33
maybe that was too vague, using `Char.IsControl(e.KeyChar)` allows you to enter backspace and move the carret (I guess you also want to allow your users with moving the cursor). If you really only want to allow backspace, according to that post you need `if (e.KeyChar == (char)8)` — bas, Mar 10 '13 at 20:36

Jakob Möllås · Answer 1 · 2013-03-10T20:45:54.923

You can check if the key pressed is a Control character using Char.IsControl(...), like this:

private void TextBox1_KeyPress(object sender, KeyPressEventArgs e)
{
    if (!Char.IsLetter(e.KeyChar) && !Char.IsControl(e.KeyChar))
        e.Handled = true;
}

If you specifically need to check only chars + Delete, use this:

private void TextBox1_KeyPress(object sender, KeyPressEventArgs e)
{
    if (!Char.IsLetter(e.KeyChar) && e.KeyChar != (char)Keys.Back)
        e.Handled = true;
}

score 0 · Answer 2 · answered Jul 23 '15 at 20:31

This is for those using VB.net. There's a weird conversion I'd never come across that took me a while to figure out.

This allows only numbers, letters, backspace and space.

Private Sub TextBox1_KeyPress(sender As Object, e As KeyPressEventArgs) Handles TextBox1.KeyPress
    e.Handled = e.KeyChar <> ChrW(Keys.Back) And Not Char.IsLetter(e.KeyChar) And Not Char.IsDigit(e.KeyChar) And Not Char.IsSeparator(e.KeyChar)
End Sub

Allow backspace button to work in validated TextBox

2 Answers2