CapDemo.GUI.User_Controls.General_Setting.txt_NumStepFail_KeyDown C# (CSharp) Method

        private void txt_NumStepFail_KeyDown(object sender, KeyEventArgs e)
        {
            nonNumberEntered = false;

            if (e.KeyCode < Keys.D0 || e.KeyCode > Keys.D9)
            {
                if (e.KeyCode < Keys.NumPad0 || e.KeyCode > Keys.NumPad9)
                {
                    if (e.KeyCode != Keys.Back)
                    {
                        nonNumberEntered = true;
                    }
                }
            }
            if (Control.ModifierKeys == Keys.Shift)
            {
                nonNumberEntered = true;
            }
        }