FindFirst, FindNext (Delphi Xe, Win7) rank is not correct

Question

I have some files in a directory. I try get these files with FindFirst and FindNext but I can't get same order on Windows 7.

C:\Test
SampleFile.0.png
SampleFile.1.png
SampleFile.2.png
SampleFile.3.png
SampleFile.4.png
SampleFile.5.png
SampleFile.6.png
SampleFile.7.png
SampleFile.8.png
SampleFile.9.png
SampleFile.10.png
SampleFile.11.png
SampleFile.12.png
SampleFile.13.png
SampleFile.14.png
SampleFile.15.png
SampleFile.16.png
SampleFile.17.png
SampleFile.18.png
SampleFile.19.png
SampleFile.20.png
SampleFile.21.png
SampleFile.22.png

When I try using my code I've got

SampleFile.0.png
SampleFile.1.png
SampleFile.10.png
SampleFile.11.png
SampleFile.12.png
SampleFile.13.png
SampleFile.14.png
SampleFile.15.png
SampleFile.16.png
SampleFile.17.png
SampleFile.18.png
SampleFile.19.png
SampleFile.2.png
SampleFile.20.png
SampleFile.21.png
.
.
.

How can I get file list on correct rank order?

Procedure Test;
var
sr : TSearchRec;
i : integer;
ListFiles : TStringList;  
begin
ListFiles := TStringList.Create;
i := FindFirst('c:\test\*.png', faDirectory, sr);
while i = 0 do begin  
ListFiles.Add(ExtractFileName(sr.FindData.cFileName));
i := FindNext(sr); 
end;
FindClose(sr);
end;  

Note : Result is still wrong, if I can use ListFiles.Sorted = True

---

I think I've a solution, created a function.

function SortFilesByName(List: TStringList; Index1, Index2: Integer): integer;
var
FileName1, FileName2: String;
i, FileNumber1, FileNumber2: Integer;
begin
  FileName1 := ChangeFileExt(ExtractFileName(List[Index1]), '');
  FileName2 := ChangeFileExt(ExtractFileName(List[Index2]), '');
  i := POS('.', FileName1)+1;
  FileNumber1 := StrToInt(Copy(FileName1, i, MaxInt));
  i := POS('.', FileName2)+1;
  FileNumber2 := StrToInt(Copy(FileName2, i, MaxInt));
  Result := (FileNumber1 - FileNumber2);
end;

I've added another line ListFiles.CustomSort(SortFilesByName); //(ListFiles,1,2):integer); before FindClose(sr);

Answer 1

As jachguate said, the sorting is done by Explorer.exe, not the filesystem. FindFirst/FindNext does not guarantee any specific sorting, including plain ASCII based, so you shouldn't rely on it. You don't, however, need to re-implement the numeric sort in Delphi. Windows exposes the one it uses as StrCmpLogicalW, which is in shlwapi.dll. The import looks like this:

function StrCmpLogicalW(psz1, psz2: PWideChar): Integer; stdcall;
  external 'shlwapi.dll'

It is possible to disable that behavior in Windows. If you want to follow the order that Windows uses, you need to call SHRestricted with the REST_NOSTRCMPLOGICAL value. If it returns true you should use AnsiCompareStr instead.

const
  // Use default CompareString instead of StrCmpLogical
  REST_NOSTRCMPLOGICAL = $4000007E;

function SHRestricted(rest: DWORD): LongBool; stdcall; external 'shell32.dll';

So your final sort function should be something like this:

function CompareFilenames(const AFilename1, AFilename2: string): Integer;
begin
  if SHRestricted(REST_NOSTRCMPLOGICAL) then
    Result := AnsiCompareStr(AFilename1, AFilename2)
  else
    Result := StrCmpLogicalW(PWideChar(AFilename1), PWideChar(AFilename2));
end;

You can cache the result of the SHRestricted call, but if you do you need to watch for the WM_SETTINGSCHANGE broadcast message and re-read it when you get one.