Delphi: Alternative to using Reset/ReadLn for text file reading

Question

i want to process a text file line by line. In the olden days i loaded the file into a StringList:

slFile := TStringList.Create();
slFile.LoadFr         


        

Answer 1

I had same problem a few years ago especially the problem of locking the file. What I did was use the low level readfile from the shellapi. I know the question is old since my answer (2 years) but perhaps my contribution could help someone in the future.

const
  BUFF_SIZE = $8000;
var
  dwread:LongWord;
  hFile: THandle;
  datafile : array [0..BUFF_SIZE-1] of char;

hFile := createfile(PChar(filename)), GENERIC_READ, FILE_SHARE_READ or FILE_SHARE_WRITE, nil, OPEN_EXISTING, FILE_ATTRIBUTE_READONLY, 0);
SetFilePointer(hFile, 0, nil, FILE_BEGIN);
myEOF := false;
try
  Readfile(hFile, datafile, BUFF_SIZE, dwread, nil);   
  while (dwread > 0) and (not myEOF) do
  begin
    if dwread = BUFF_SIZE then
    begin
      apos := LastDelimiter(#10#13, datafile);
      if apos = BUFF_SIZE then inc(apos);
      SetFilePointer(hFile, aPos-BUFF_SIZE, nil, FILE_CURRENT);
    end
    else myEOF := true;
    Readfile(hFile, datafile, BUFF_SIZE, dwread, nil);
  end;
finally
   closehandle(hFile);
end;

For me the speed improvement appeared to be significant.