怎么判断一个程序正在运行，不能让程序重复启动

修改工程文件：
var hMutex: Hwnd;
    Ret: integer;
begin
  Application.Initialize;
  Application.Title:='Program Run Once Test':
  hMutex:=CreateMutex(nil,false,'Program Run Once Test');
  Ret:=GetLastError;
  if Ret<>Error_Already_Exists then
     begin
       Application.Create(TForm1,Form1);
       Application.Run;
     end
  else
    Application.MessageBox('This Program is running','Warning',MB_OK);
  ReleaseMutex(hMutex）；
end;

给你一个我修改后的构件
{
JustOne v1.1 - A Delphi Component
By: Steven L. Keyser
    email: 71214,[email protected]  ####################################################################
  # Modified By He Kai, ZIQ, China, email : [email protected]
  #  Delphi 3.0                    26-Jun-1998
  # In order to use in Win95, I Modified the program, the original can only
  #  use in win31
  ####################################################################    Purpose: JustOne is a component which makes it easy to limit the
    number of your application's instances to just one.  If a second
    instance of your application starts, the first instance is brought
    to the front and given the focus (or restored if it was minimized
    to an icon).  The second instance then halts.}
unit Justone;interfaceuses
  SysUtils, Windows, Messages, Classes, Graphics, Controls,
  Forms, Dialogs, DsgnIntf;type
TMyDataType = record
Name : string;
end;type
  TJustOne = class(TComponent)
  private
  public
    constructor Create(AOwner:TComponent); override;
    destructor Destroy; override;
    procedure GoToPreviousInstance;
  published
  end;procedure Register;type
  PHWND = ^HWND;
  // Modified By He Kai
  // function EnumFunc(Wnd:HWND; TargetWindow:PHWND): boolean; export;
  function EnumFunc(Wnd:HWND; TargetWindow:PHWND): boolean; export; stdcall;implementation{########################################################################}
procedure Register;
{If you want, replace 'SLicK' with whichever component page you want
JustOne to show up on.}
begin
  RegisterComponents('HK Invisible', [TJustOne]);
end;{########################################################################}
// Modified by He Kai
{
function EnumFunc(Wnd:HWND; TargetWindow:PHWND): boolean;
var
  ClassName : array[0..30] of char;
begin
  result := TRUE;
  if GetWindowWord(Wnd,GWW_HINSTANCE) = hPrevInst then
     begin
       GetClassName(Wnd,ClassName,30);
       if StrIComp(ClassName,'TApplication') = 0 then
         begin
           TargetWindow^ := Wnd;
           result := FALSE;
         end;
     end;
end;
}
// Modified By He Kai
// function EnumFunc(Wnd:HWND; TargetWindow:PHWND): boolean;
function EnumFunc(Wnd:HWND; TargetWindow:PHWND): boolean;
var
  TheClassName  : array[0..200] of char;
  TheTitleName  : array[0..200] of char;
  ThisTitleName : String;
begin
  result := TRUE;
  GetClassName(Wnd,TheClassName,200);
  if StrIComp( TheClassName,'TApplication' ) = 0 then
  begin
    GetWindowText( Wnd, TheTitleName, 200 );
    ThisTitleName := Application.Title;
    If (Wnd<>Application.Handle) And (StrIComp( PChar(ThisTitleName), TheTitleName ) = 0) Then
    Begin
      TargetWindow^ := Wnd;
      result := FALSE;
    End;
  End;
end;{########################################################################}
procedure TJustOne.GotoPreviousInstance;
var
  PrevInstWnd : HWND;
begin
  PrevInstWnd := 0;
  EnumWindows(@EnumFunc,longint(@PrevInstWnd));  if PrevInstWnd <> 0 then
  Begin
    if IsIconic(PrevInstWnd) then
      ShowWindow(PrevInstWnd,SW_RESTORE)
    else
      SetForegroundWindow(PrevInstWnd);
    FlashWindow(PrevInstWnd, True );
    Sleep(450);
    FlashWindow(PrevInstWnd, false );
    Sleep(450);
    FlashWindow(PrevInstWnd, True );
    Sleep(450);
    FlashWindow(PrevInstWnd, false );
    Halt;
  End
end;{########################################################################}
constructor TJustOne.Create(AOwner:TComponent);
begin
  inherited Create(AOwner);
// modified by He Kai
// if hPrevInst <> 0 then
//    begin
  GotoPreviousInstance;
//      halt;
//    end;
end;{########################################################################}
destructor TJustOne.Destroy;
begin
  inherited Destroy;
end;{########################################################################}
end.

Apollo47(): 错误 Hwnd CreateMutex ReleaseMutex 没有定义啊　现在怎么版啊

调试易

怎么判断一个程序正在运行，不能让程序重复启动

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