Delphi ActiveX

Socket Send/Receive 16-bit Integers

Demonstrates sending and receiving 16-bit integers over a socket connection using either big-endian or little-endian byte ordering. Delphi ActiveX

uses
    Winapi.Windows, Winapi.Messages, System.SysUtils, System.Variants, System.Classes, Vcl.Graphics,
    Vcl.Controls, Vcl.Forms, Vcl.Dialogs, Vcl.StdCtrls, Chilkat_TLB;

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Integer;
sock: TChilkatSocket;
useTls: Integer;
port: Integer;
maxWaitMs: Integer;
value: Integer;
bigEndian: Integer;
hexStr: WideString;

begin
success := 0;

// This example requires the Chilkat API to have been previously unlocked.
// See Global Unlock Sample for sample code.

sock := TChilkatSocket.Create(Self);

// --------------------------------------------------------------------
// This example uses the public TCP echo service at https://tcpbin.com/
// --------------------------------------------------------------------

useTls := 0;
port := 4242;
maxWaitMs := 5000;
success := sock.Connect('tcpbin.com',port,useTls,maxWaitMs);
if (success = 0) then
  begin
    Memo1.Lines.Add(sock.LastErrorText);
    Exit;
  end;

// Wait a max of 2 seconds for a response..
sock.MaxReadIdleMs := 2000;

// Send a 16-bit integer using big-endian byte ordering (also called network byte order)
// 12022 decimal = 2EF6 hex
value := 12022;
bigEndian := 1;
sock.SendInt16(value,bigEndian);
// Send it again, because we'll read it two different ways..
sock.SendInt16(value,bigEndian);

// The tcpbin.com echo server only echoes after receiving an LF (linefeed char)
sock.SendByte(10);

// Let's see hex values of the 2 bytes sent in network byte order (big-endian)
// (The echo server sends back exactly the bytes received.)
hexStr := sock.ReceiveNBytesENC(2,'hex');

// In the big-ending byte order, the byte order is most significant byte to least significant,
// therefore we should see the bytes in the order 0x2E 0xF6.
Memo1.Lines.Add('Expecting big-endian 2EF6');
Memo1.Lines.Add(hexStr);

// Let's read directly to an integer..
success := sock.ReceiveInt16(bigEndian,1);
Memo1.Lines.Add('Expecting 12022');
Memo1.Lines.Add('Received: ' + IntToStr(sock.ReceivedInt));

// Consume the LF that gets echoed back..
sock.ReceiveByte(1);

// --------------------------------------------------------------------
// Let's do the same thing, but with little-endian byte ordering.

Memo1.Lines.Add('----');

// 12022 decimal = 2EF6 hex, but little-endian byte ordering will send the bytes in the order 0xF6 0x2E
value := 12022;
bigEndian := 0;
sock.SendInt16(value,bigEndian);
sock.SendInt16(value,bigEndian);
sock.SendByte(10);

hexStr := sock.ReceiveNBytesENC(2,'hex');

Memo1.Lines.Add('Expecting little-endian F62E');
Memo1.Lines.Add(hexStr);

success := sock.ReceiveInt16(bigEndian,1);
Memo1.Lines.Add('Expecting 12022');
Memo1.Lines.Add('Received: ' + IntToStr(sock.ReceivedInt));

// Consume the LF that gets echoed back..
sock.ReceiveByte(1);

sock.Close(1000);

// Output:

// Expecting big-endian 2EF6
// 2EF6
// Expecting 12022
// Received: 12022
// ----
// Expecting little-endian F62E
// F62E
// Expecting 12022
// Received: 12022
end;