Search only files that match part of the name in a directory

Question

I have the following problem

In a given directory I will need to create files that meet the following criteria.

DOCUMENTO_DDMM_SEQ.txt

Where

• Document : Any number that may or may not be repeated
• DDMM : Day + Month of current date
• SEQ : Global Directory Sequence Starting at 001

In order to generate the correct sequence I need to know the value of the last sequence (higher value)

I was able to approach reading all the files from the directory to a list and iterating the list in search of the last value, but this method is very bad, because the directory is the user’s choice and it can use a directory that contains many files, making this research very slow. Wanted something that already filtered the files before I had to iterate the list.

Any suggestion will be evaluated

Answer 1

I was able to do what I wanted using Tsearchrec as follows.

procedure TFrm....
  var search : TSearchRec; // Unit SysUtils
    filename, dirname : String;
    seq, i : Integer;
Begin
  // (...)
  if not SelectDirectory('Selecione o diretório', 'arqs', dirname) then // Unit FileCtrl
    begin
       Application.MessageBox('Sem destino', APPNAME, MB_OK+MB_ICONERROR);
       Exit;
    end;
  try 
    // Pesquisando o diretório corrente para gerar arquivos únicos
    if (FindFirst(dirname + '*_' + FormatDateTime('ddmm', Date) + '_*.txt',
                    faArchive,
                    searchResult) = 0 ) then
      begin
        repeat
          // Extraindo o sequencial do arquivo
          i := LastDelimiter('_', searchResult.Name);
          if (TryStrToInt(copy(searchResult.Name, i, 3), i)) then
            seq := Max(i, seq);
        until FindNext(searchResult) <> 0;
        FindClose(searchResult);
      end;

    filename := NUMERO_DOCUMENTO + '_' +
                FormatDateTime('ddmm', Date) + '_' +
                LPad(IntToStr(seq + 1), 3, '0') + '.txt'; // LPad função privada de padding à esquerda
    // Garantindo que não existe arquivo com a nomenclatura passada
    while FileExists(dirname + filename) do
      begin
        seq := seq + 1;
        filename := NUMERO_DOCUMENTO  + '_' +
                    FormatDateTime('ddmm', Date) + '_' +
                    LPad(IntToStr(seq + 1), 3, '0') + '.txt';

      end;  

    // (Outros códigos ...)
End;
End.

One thing that helped me with this code was the use of TryStrToInt, because it allowed me to prevent an unfinished name in _999.txt from causing the application to generate a Exception conversion.

Apparently I could have problems when the sequence arrived in 999 because the next one to be generated would be _1000.txt and instead of being able to fetch the value 1000, as I am limiting to 3 characters will end up picking 100 and iterating in the existence check until the 1001. It’ll work out the wrong way.

A solution would be to find the position of ". txt" to calculate the number of characters to be used for both the function copy how much for the padding.