1   
2   unit Unit1;
3   
4   interface
5   
6   uses
7     Windows, Messages, SysUtils, Variants, Classes, Graphics, Controls, Forms,
8     Dialogs, StdCtrls;
9   
10  type
11    TForm1 = class(TForm)
12      Button1: TButton;
13      OpenDialog1: TOpenDialog;
14      procedure Button1Click(Sender: TObject);
15    private
16      { Private declarations }
17    public
18      { Public declarations }
19    end;
20  
21  var
22    Form1: TForm1;
23  
24  implementation
25  
26  {$R *.dfm}
27  
28  function IsFileInUse(const fName: TFileName): Boolean;
29  var
30    HFileRes: HFILE;
31  begin
32    Result := False;
33    HFileRes := CreateFile(PChar(fName),
34                           GENERIC_READ or GENERIC_WRITE,
35                           0,
36                           nil,
37                           OPEN_EXISTING,
38                           FILE_ATTRIBUTE_NORMAL,
39                           0);
40    Result := (HFileRes = INVALID_HANDLE_VALUE);
41    if not Result then
42      CloseHandle(HFileRes);
43  end;
44  
45  
46  procedure TForm1.Button1Click(Sender: TObject);
47  begin
48    if OpenDialog1.Execute then
49      if IsFileInUse(Opendialog1.FileName) then
50        ShowMessage('File is in use!')
51  else
52        ShowMessage('File NOT in use!');
53  
54  end;
55  end.
56