Zip files

Starting with version 2.00, either the Source or the Target directory (but not both) may be replaced as storage location by a compressed file. Directory Compare uses the popular zip format for compressed files: they are useful to save space, but adding and deleting files (as opposed to extracting files) takes time, especially if an high Compression level (see Options) is used.

Since the main goal of Directory Compare is to compare and synchronize directories, not zip files, and the latter are not directories, they suffer some restrictions (apart from being slower when adding and deleting files):

  1. At least one of Source and Target must be a true directory. You cannot use Directory Compare to compare and synchronize zip files directly. (Of course, you can use it to extract one of the zip files to a temporary directory and then compare and synchronize this directory first with the second zip file and then, if any update has been made to the temporary directory, with the original zip file.)
  2. Some options apply only to zip files and are listed in a separate sheet in the Options dialog box.
  3. Items deleted from zip files are not sent to the recycle bin, so the Delete... and Eliminate... menus are equivalent when applied to zipped items.
  4. Since zipped items are not independent files, they cannot be executed or viewed with the Open... menus or double clicking on them with the right values on the Options dialog box. For the same reason, you cannot compare a zipped item with a file with the External Compare program. Of course, the program could extract the item to a temporary location and execute it or launch the external program with its file specification; but who would the temporary file when it is no longer necessary?
  5. By default, when the Display icons option is selected, an item that exists only in a zip file (and not in a directory) will be assigned the icon. However, if you are ready to pay the time penalty, you may select the If necessary unzip file to get its icon option and the program will try harder to get the right icon.
  6. Since apparently empty directories cannot be stored in zip files, the List, Copy and Delete directories option is ignored if either the Target or the Source is a zip file, and directories will not get separate entries in the main list.
  7. If Short file names is selected files will be stored in a zip file with its short name, but already stored files will be listed with the name they have in the zip file, because there is no reliable way to predict the short name Windows will assign to them when extracted to a disk.
  8. Aborting the adding or removing of items in a zip file (which is sometimes necessary if a very long zip operation has been inadvertently started) may lead to a corrupted zip file. So, for security, you may want to select the Backup zip file... option to make sure that, at least, you do not lose the original zip file. This is another reason to make sure that you select your Temporary directory in your bigger and faster disk.
  9. The code to manage zip files may issue error messages not available with files in directories.