unit Cthread;

interface

uses
  Windows, Messages, SysUtils, Classes, Graphics, Controls, Forms, Dialogs,
  StdCtrls;

type
  TForm1 = class(TForm)
    Button1: TButton;
    Edit1: TEdit;
    procedure Button1Click(Sender: TObject);
    procedure FormDestroy(Sender: TObject);
  private
  public
    { Public declarations }
  end;

var
  Form1: TForm1;
  ThreadHandle: THandle;                 // holds the handles the the threads
  ThreadHandle2: THandle;
  CriticalSection: TRTLCriticalSection;  // holds the critical section info

implementation

{$R *.DFM}

Function ThreadFunc(Info: Pointer): Integer; stdcall;
Var
  Count : Integer;    // general loop control variable
Begin
  {performing the EnterCriticalSection function prevents the second thread
   from executing until this thread leaves the critical section}
  EnterCriticalSection(CriticalSection);

  {show a visual display}
  for Count := 0 to 100 Do
  begin
    Form1.Edit1.Text := IntToStr(Count);
    Sleep(1);
  end;

  {display a message}
  Form1.Edit1.Text := 'Hello from the thread!';

  {pause for a second}
  Sleep(1000);

  {leave the critical section and exit the thread}
  LeaveCriticalSection(CriticalSection);
  ExitThread(4);
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  ThreadId1, ThreadId2: DWORD;   // holds the created thread identifiers
begin
  {initialize the critical section information}
  InitializeCriticalSection(CriticalSection);

  {create and execute the first thread}
  ThreadHandle := CreateThread(nil, 0, @ThreadFunc, nil, 0, ThreadId1);

  {create and execute the second thread}
  ThreadHandle2 := CreateThread(nil, 0, @ThreadFunc, nil, 0, ThreadId2);
end;

procedure TForm1.FormDestroy(Sender: TObject);
begin
  {we are done, so destroy the critical section information}
  DeleteCriticalSection(CriticalSection);
end;

end.