Allow backspace in keypress event

Question

I want only 4 digit numbers and delete and backspace.

Answer 1

Private Sub TxtPStof_KeyPress(ByVal sender As System.Object, ByVal e As System.Windows.Forms.KeyPressEventArgs) Handles TxtPStof.KeyPress 

    if e.KeyChar <> ControlChars.Back then
        e.Handled = Not (Char.IsDigit(e.KeyChar)  
    end if

End Sub