1         private void txt_bytesendid_KeyPress(object sender, KeyPressEventArgs e)
 2         {
 3             if ((e.KeyChar >= 'a' && e.KeyChar <= 'f') || (e.KeyChar >= 'A' && e.KeyChar <= 'F')
 4                || (e.KeyChar >= '0' && e.KeyChar <= '9') 
 5                || e.KeyChar == 32 || e.KeyChar == 8 || e.KeyChar == 16)
 6             {//32 Space,8 Back,13 Enter,20 Capital,46 Delete,16 ShiftKey
 7                 e.Handled = false;//允许字符键入
 8             }
 9             else
10             {
11                 MessageBox.Show("请输入16进制字符组合(“0-9”“A-F”“a-f”“ ”)！", "警告", MessageBoxButtons.OK, MessageBoxIcon.Warning);
12                 e.Handled = true;//阻拦字符键入
13             }
14         }