Title: How to check if a file can be opened
function IsFileInUse(const fName: TFileName): Boolean;
var
HFileRes: HFILE;
begin
Result := False;
HFileRes := CreateFile(PChar(fName),
GENERIC_READ or GENERIC_WRITE,
0,
nil,
OPEN_EXISTING,
FILE_ATTRIBUTE_NORMAL,
0);
Result := (HFileRes = INVALID_HANDLE_VALUE);
if not Result then
CloseHandle(HFileRes);
end;
procedure TForm1.Button1Click(Sender: TObject);
begin
if OpenDialog1.Execute then
if IsFileInUse(Opendialog1.FileName) then
ShowMessage('File is in use!');
end;