static int countFilesInZip(File inZip) ctex {
  temp ZipFile zipFile = new ZipFile(inZip);
  ret countFilesInZip(zipFile);
}
      
static int countFilesInZip(ZipFile zipFile) ctex {
  int n = 0;
  Enumeration entries = zipFile.entries();
  while (entries.hasMoreElements()) {
    ZipEntry entry = cast entries.nextElement(); 
      if (!entry.isDirectory())
        ++n;
  }
  ret n;
}

Began life as a copy of #1002029