abusing LISTBOXes (VB6 port)

[Erich Schulman]

http://www.vb-helper.com/howto_list_subdirectories.html seems to be using a collection object as a variable-length array. We don't have collection objects or C++esque vectors, so it seems a hidden LISTBOX would be an easy way to provide the illusion of a variable-length array. Are there any pitfalls to be aware of, besides the Win9x limit of 32767 elements in a LISTBOX?

[José Roca]

Is there any reason you can't use an array of strings to store the names of the subdirectories?

[Erich Schulman]

You don't know the actual number in advance. Even if I calculated the absolute maximum number of directories a NTFS partition could hold, there is still the possibility of reading multiple NTFS partitions and/or mounting a ext3 partition or non-partitioned media.

I could DIM for 0 TO 999999 and assume I will probably never run out, but I tend to have an aversion to 640K ought to be enough for anyone assumptions. But I think I would rather allocate an enormous array than have to deal with periodic REDIM PRESERVE's.

[Michael Mattias]

An "array of strings" need not be a PB Array requiring DIM/REDIM.

It can be a simple delimited string, with each string ending with a known delimiter character such as $NUL or $TAB. Just concatenate as you build. If you want that data in a PB array for manipulation purposes after it's built, just PARSE the string into that array at that time.

BTW, re REDIM PRESERVE usage.... I would like a nickel for everytime I've written code similar to ..

 WHILE condition 
      INCR  nITem           ' add an item to array 
      IF nItem > UBOUND (target_array) THEN 
         REDIM PRESERVE target_array (nItem + %ITEM_INCREMENT) 
      END IF 
 Wend
 REDIM PRESERVE target_array (nITem)   ' size to fit when done

Without volumes it's hard to tell if either approach makes sense, but if you were thinking about a "hidden listbox" I think it's safe to say your volumes are low enough for either method to work.

MCM

[Chris Holbrook]

...or use a tree structure which would allow sorting to be done as the tree is built. Or even a tree inside a dynamic string.