delphi取文件创建时间问题请教?

Question

procedure TForm1.Button18Click(Sender: TObject);
var
    FileHandle:Integer;
    FileTime:TFileTime;
    LocalFileTime:TFileTime;
    SystemTime:TSystemTime;
begin
    if(opendialog1.Execute) then
    edit4.Text:=opendialog1.FileName;
    FileHandle:=FileOpen(opendialog1.FileName,fmOpenWrite or fmShareDenyNone);
    if(FileHandle>0) then
    begin
      showmessage('good');
      FileTime.dwLowDateTime:=0;
      FileTime.dwHighDateTime:=0;
      Windows.GetFileTime(FileHandle,@FileTime,nil,nil);
      FileTimeToLocalFileTime(FileTime, LocalFileTime);
      FileTime:=LocalFileTime;
      FileClose(FileHandle);
      if FileTimeToSystemTime(FileTime, SystemTime) then
      edit7.Text := SystemTimeToDateTime(SystemTime);
    end
    else
      showmessage('error');
end;
我想取文件的创建时间在edit7.text里显示出来.怎么不行?程序怎么改?
顺便解释一下
FileTimeToLocalFileTime(FileTime, LocalFileTime);
      FileTime:=LocalFileTime;
这个转换有什么用啊?
还有FileTimeToSystemTime为什么要转化后输出?

Answer 1

edit7.Text:=DateTimeToStr(SystemTimeToDateTime(SystemTime));

Answer 2

procedure TForm1.Button1Click(Sender: TObject);
var
   f: file of Byte;
   size: Longint;
   S: string;
   FileName : string;
begin
  begin
  FileName := 'd:\aa.txt';
  AssignFile(f,FileName);
    Reset(f);
    try
      size := FileSize(f);
      S := 'File size in bytes: ' + IntToStr(size);
      edit1.Text := DateTimeToStr(FileDateToDateTime(FileAge(FileName)));
    finally
      CloseFile(f);
    end;
  end;
end;

Answer 3

function GetFileModify(FileName:string):TDateTime;
//取得文件的最后修改时间
var
  sr: TSearchRec;
  DT:Tdatetime;
  FileTime: TFileTime;
  DFT: DWORD;
begin
  if findfirst(FileName,faanyfile,sr)=0 then
  begin
    FileTimeToLocalFileTime(SR.FINDdata.ftLastWriteTime, FileTime);
    FileTimeToDosDateTime(FileTime, LongRec(DFT).HI, LongRec(DFT).LO);
    DT:=filedatetodatetime(dft);
    Result:=DT;
  end 
end;