无类型文件Demo

var  sHeadFile: string;  F: file;  B: array[0..2] of Byte;  D, i: Integer;begin  sHeadFile := '';  if edt1.Text = '' then  begin    ShowMessage('请选择一个文件！');    Exit;  end;  if FileExists(edt1.Text) then  begin    D := GetFileAttributesA(pchar(edt1.text));    if (D = -1) or (D = 33) or (D = 39) then    begin      ShowMessage('文件不能为只读属性,读取头部特征失败！');      Exit;    end;    AssignFile(F, edt1.Text);    Reset(f, 1);    BlockRead(F, B, 3);    for i := Low(B) to High(B) do    begin      sHeadFile := sHeadFile + (inttohex(B[i], 2));    end;    mmo1.Lines.Add('“' + ExtractFileName(UpperCase(edt1.Text)) + '”头部文件特征是：' + sHeadFile);    CloseFile(f);    if UpperCase(sHeadFile) = 'FEEF01' then      ShowMessage('“' + ExtractFileName(UpperCase(edt1.Text)) + '“是镜像文件')    else      ShowMessage('“' + ExtractFileName(UpperCase(edt1.Text)) + '”不是镜像文件！');  end  else    ShowMessage('“' + edt1.Text + '” 文件未找到！');end;