Question

I am an engineer and not a software programmer, so please excuse my ignorance.

I have written a Delphi(7SE) program to read “real” datatype from a USB port connected to two digital thermometers.

I have completed this much of the program.

What I have not completed as yet is explained by the following:

I wish to save this “real” data to a Binary File(s). A text file would be fine as well, but i’m concerned about having a big data file.

I also wish to read this data back from the Binary/Text File to display the data using my Delphi application.

I don’t think this would be too difficult. I currently save my data in .CSV format.

The twist here is that the binary file should contain data from different sessions initiated by the user of my application.

So when I click on say, a button called “ historical” data, a new window/form would pop up that would show different session times that I had started & stopped from earlier times. Then a session would be selected and data then retrieved for displaying.

Can this be done in one binary files or would you have to use 2 files: one for the “real” data and another which indexes the different session times?

My requirement for this way of saving binary data is that I would not have to keep typing in filenames and therefore keeping track of many data files.

For example a thermo.hst(historical data) and a thermo.idx (index file) file would contain all the information such as actual temp data, time of read data, session start & end times etc.

Any useful pointers and hopefully code with as much detail would be greatly appreciated.

Answer 1

I hope this sample code isn’t too late to be helpful.

(I’ve added this as another answer from me so that I can cleanly list the code. If this or my previous post answers your question, please click the answer icon so I get reputation points!)

Below is some rough code that shows how to read the sections in an ini file and find the largest filename. I confirmed it compiles and seems to return valid values, but you’ll need confirm it does what you need. It’s more to show you the idea…

Note that if your data filenames have an extension, you’ll have add code to remove the extension in my sample code using something like: FileName := ChangeFileExt(Filename, ”).

  // Call with an open inifile.  Returns the name of the next filename, or '' if trouble
  Function GetNextFileName( const IniFile: TInifile):String;
  const
    BASE_FILENAME = 'File.'; // sections in the ini file will be [File.1], [File.2], ... [File.100], etc.
  var
    Sections: TStringList;
    NumericPartAsString: String;
    NumericPartAsInteger: Integer;
    ListIndex: Integer;
    LargestFileNumberSeenSoFar: Integer;
  begin
    Result := '';
    Sections := TStringList.Create;
    IniFile.ReadSections(Sections); // fills StringList with the names of all sections in the ini file
    if( Sections.Count = 0) then
      Result := BASE_FILENAME + '1'
    else
      begin  // find largest extension
        LargestFileNumberSeenSoFar := -1;
        ListIndex := 0;
        while ListIndex <= (Sections.Count - 1) do  // for every string (which is also a filename) in the string list:
          begin
            NumericPartAsString := StringReplace(Sections.Strings[ListIndex], BASE_FILENAME, '', []); // remove base filename
            if (NumericPartAsString <> '') then
              begin
                NumericPartAsInteger := StrToIntDef(NumericPartAsString, -1);
                if (NumericPartAsInteger > LargestFileNumberSeenSoFar) then
                  LargestFileNumberSeenSoFar := NumericPartAsInteger;
              end;
            inc(ListIndex);
          end;
        if (LargestFileNumberSeenSoFar > -1) then
          Result := BASE_FILENAME + IntToStr(LargestFileNumberSeenSoFar + 1);
      end;
    Sections.Free;
  end; { GetNextFileName }

  procedure TForm1.Button1Click(Sender: TObject);
  var
    IniFile: TInifile;
    NewFileName: String;
  begin
    IniFile := TInifile.Create('c:\junk\ini.ini');
    NewFileName := GetNextFileName(Inifile);
    if (NewFileName = '') then
      ShowMessage('Error finding new filename')
    else
      ShowMessage('New filename is ' + NewFileName);
    IniFile.Free;
  end;