Pascal (Lazarus/Delphi)

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. Pascal (Lazarus/Delphi)

program ChilkatDemo;

// Demonstrates using the Chilkat Pascal wrapper via the C bridge DLL.
// Builds as a console application under Lazarus (FPC) or Delphi.

{$IFDEF FPC}
  {$MODE DELPHI}
{$ENDIF}
{$APPTYPE CONSOLE}

uses
  {$IFDEF UNIX}
  cthreads,
  {$ENDIF}
  SysUtils,
  CkDllLoader,
  Chilkat.Socket;

// ---------------------------------------------------------------------------

procedure RunDemo;
var
  success: Boolean;
  sock: TSocket;
  useTls: Boolean;
  port: Integer;
  maxWaitMs: Integer;
  value: Integer;
  bigEndian: Boolean;
  hexStr: string;

begin
  success := False;

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

  sock := TSocket.Create;

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

  useTls := False;
  port := 4242;
  maxWaitMs := 5000;
  success := sock.Connect('tcpbin.com',port,useTls,maxWaitMs);
  if (success = False) then
    begin
      WriteLn(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 := True;
  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.
  WriteLn('Expecting big-endian 2EF6');
  WriteLn(hexStr);

  //  Let's read directly to an integer..
  success := sock.ReceiveInt16(bigEndian,True);
  WriteLn('Expecting 12022');
  WriteLn('Received: ' + sock.ReceivedInt);

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

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

  WriteLn('----');

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

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

  WriteLn('Expecting little-endian F62E');
  WriteLn(hexStr);

  success := sock.ReceiveInt16(bigEndian,True);
  WriteLn('Expecting 12022');
  WriteLn('Received: ' + sock.ReceivedInt);

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

  sock.Close(1000);

  //  Output:

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


  sock.Free;

end;

// ---------------------------------------------------------------------------

begin

  try
    RunDemo;
  except
    on E: Exception do
      WriteLn('Unhandled exception: ', E.ClassName, ': ', E.Message);
  end;

  WriteLn;
  {$IFDEF MSWINDOWS}
  WriteLn('Press Enter to exit...');
  ReadLn;
  {$ENDIF}
end.