EditMask (C++)

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Description

This example uses three mask edit components on a form, where the third mask edit box is set to be read-only. When the application runs, it initializes the mask edit boxes to contain the empty string, to use the Courier font, and to use a particular mask, corresponding to IP address coding conventions. The mask edit boxes display the IP address, the subnet mask and the subnet address respectively. When you exit the subnet mask edit box, the subnet address is automatically computed using bit-wise AND operations and displayed in the third mask edit box. An additional test is made to assure that the values in the IP address and in the subnet mask are in the interval from 0 through 255, as this validation test cannot be accomplished using the edit mask property alone.

Code

__fastcall TForm1::TForm1(TComponent* Owner)
  : TForm(Owner)
{
  // Initialize the mask edit boxes to contain the empty string.
  MaskEdit1->Text = "";
  MaskEdit2->Text = "";
  MaskEdit3->Text = "";

  // Use the Courier font in the mask edit boxes.
  MaskEdit1->Font->Name = "Courier";
  MaskEdit2->Font->Name = "Courier";
  MaskEdit3->Font->Name = "Courier";

  // Initialize the mask of each mask edit box
  // according to IP address coding conventions.
  MaskEdit1->EditMask = "!099.099.099.099;1; ";
  MaskEdit2->EditMask = "!099.099.099.099;1; ";
  MaskEdit3->EditMask = "!099.099.099.099;1; ";

  MaskEdit2->OnExit = MaskEdit2Exit;
}

void __fastcall TForm1::MaskEdit2Exit(TObject *Sender)
{
  // Extract the net and host address from the IP.
  String IP = MaskEdit1->Text;
  int net1 = IP.SubString(0, 3).TrimRight().ToInt();
  int net2 = IP.SubString(5, 3).TrimRight().ToInt();
  int host1 = IP.SubString(9, 3).TrimRight().ToInt();
  int host2 = IP.SubString(13, 3).TrimRight().ToInt();

  // A range test that you cannot validate through edit masks
  if (net1 < 0 || net1 > 255 ||
      net2 < 0 || net2 > 255 ||
      host1 < 0 || host1 > 255 ||
      host2 < 0 || host2 > 255)
    throw(Exception("Not a valid IP address."));

  // Extract the net and host mask from the subnet mask.
  String mask = MaskEdit2->Text;
  int netmask1 = mask.SubString(0, 3).TrimRight().ToInt();
  int netmask2 = mask.SubString(5, 3).TrimRight().ToInt();
  int hostmask1 = mask.SubString(9, 3).TrimRight().ToInt();
  int hostmask2 = mask.SubString(13, 3).TrimRight().ToInt();

  // A range test that you cannot validate through edit masks
  if (netmask1 < 0 || netmask1 > 255 ||
      netmask2 < 0 || netmask2 > 255 ||
      hostmask1 < 0 || hostmask1 > 255 ||
      hostmask2 < 0 || hostmask2 > 255)
    throw(Exception("Not a valid subnet mask."));

  // Compute the subnet address using bit-wise AND.
  int sub_net1 = net1 & netmask1;
  int sub_net2 = net2 & netmask2;
  int sub_host1 = host1 & hostmask1;
  int sub_host2 = host2 & hostmask2;

  // Display the subnet address.
  MaskEdit3->Text =
    String(sub_net1) + "." + String(sub_net2) + "." +
    String(sub_host1) + "." + String(sub_host2);
}

Uses

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