How to get the subdirectories?

I have been searching a lot for a way to get the subdirectories of any directory. I haven't found a way yet so I hope you can help me.

If all you want is to obtain a list of subdirectories within a specified path, you can use FindFirst/FindNext as in the following code:

procedure Form1.GetDirList(sPath: string);
var
  Found:     Integer;
  SearchRec: TSearchRec;
begin
  Found := SysUtils.FindFirst(IncludeTrailingBackslash(sPath) 
+ '*.*', faDirectory, SearchRec);
  try
    while Found = 0 do
    begin
      if ((SearchRec.Attr and faDirectory) = faDirectory) and (SearchRec.Name[1] <> '.') then
        ListBox1.Items.Add(SearchRec.Name);
      Found := SysUtils.FindNext(SearchRec);
    end;
  finally
    SysUtils.FindClose(SearchRec);
  end;
end;

However, if you want to get the subdirectories within a specified path AND the subdirectories under those, then you need to use a recursive procedure. A recursive procedure (or function) is one that calls itself. (NOTE: The most important thing to remember when creating recursive methods is to make sure there is some condition to exit from the method at some point!) Here is a procedure that will obtain all subdirectories from a specified path down:

procedure Form1.GetSubDirList(sPath: string);
var
  Found:     Integer;
  SearchRec: TSearchRec;
begin
  Found := SysUtils.FindFirst(IncludeTrailingBackslash(sPath) + '*.*', faDirectory, SearchRec);
  try
    while Found = 0 do
    begin
      if ((SearchRec.Attr and faDirectory) = faDirectory) and (SearchRec.Name[1] <> '.') then
      begin
        ListBox1.Items.Add(IncludeTrailingBackslash(sPath) + SearchRec.Name);
        Application.ProcessMessages;
        // Recursive method call
        GetSubDirList(IncludeTrailingBackslash(sPath) + SearchRec.Name);
      end;
      Found := SysUtils.FindNext(SearchRec);
    end;
  finally
    SysUtils.FindClose(SearchRec);
  end;
end;

Hope this helps,
Larry

Larry J. Rutledge

Analyst

Prestwood Software

www.prestwood.com

A while back there was an article, some forum discussion, and a free component for extending the functionality of FindFirst and FindNext at
Old UBB Archived Link: [URL=http://delphi.about.com/]http://delphi.about.com/[/URL]

Rick Carter
Chair, Delphi/Paradox SIG
Cincinnati PC Users Group

We use code that is very similiar to this, but we don't call Application.ProcessMessages. What is the benefit of making that call here? Is it advisable to do this before making a recursive call, and if so, why?

The recursive call to GetSubDirList doesn't trigger the Windows Event Handler until it returns from the last call. So "Application.ProcessMessages" triggers the event handler to repaint the lines in the list box as they are being written.