Delphi DLL

Socket Receive String Until Specific Byte Value is Received

Demonstrates the Chilkat Socket ReceiveStringUntilByte method. Delphi DLL

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

...

procedure TForm1.Button1Click(Sender: TObject);
var
success: Boolean;
sock: HCkSocket;
useTls: Boolean;
port: Integer;
maxWaitMs: Integer;
lookForByte: Integer;
s1: PWideChar;
s2: PWideChar;

begin
success := False;

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

sock := CkSocket_Create();

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

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

// Wait a max of 2 seconds for a response..
CkSocket_putMaxReadIdleMs(sock,2000);

// Send some strings, each terminated by a 0 byte.
CkSocket_SendString(sock,'This is the 1st string');
CkSocket_SendByte(sock,0);
CkSocket_SendString(sock,'This is string number 2');
CkSocket_SendByte(sock,0);

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

// Now let's receive what is echoed back....
// Receive each string and the NULL byte.
// The call to ReceiveStringUntilByte will receive incoming data until the lookForByte is encountered.
// The lookForByte is receive and discarded (it is not returned in the string)
lookForByte := 0;
s1 := CkSocket__receiveStringUntilByte(sock,lookForByte);
if (CkSocket_getLastMethodSuccess(sock) = False) then
  begin
    Memo1.Lines.Add(CkSocket__lastErrorText(sock));
    Exit;
  end;
Memo1.Lines.Add(s1);

s2 := CkSocket__receiveStringUntilByte(sock,lookForByte);
if (CkSocket_getLastMethodSuccess(sock) = False) then
  begin
    Memo1.Lines.Add(CkSocket__lastErrorText(sock));
    Exit;
  end;
Memo1.Lines.Add(s2);

// The echo server will also echo back the final LF
CkSocket_ReceiveByte(sock,True);
maxWaitMs := 100;
CkSocket_Close(sock,100);

// Output:
// This is the 1st string
// This is string number 2

CkSocket_Dispose(sock);

end;