zip_get_num_entries —
get number of files in archive
#include <zip.h>
zip_int64_t
  
  zip_get_num_entries(zip_t
    *archive, zip_flags_t
    flags);
The zip_get_num_entries() function returns the number of
  files in archive. If flags is set
  to ZIP_FL_UNCHANGED, the original number of entries is
  returned.
zip_get_num_entries() returns the number of files in the
  zip archive, or -1 if archive is
  NULL.
zip_get_num_entries() was added in libzip 0.10. In
  libzip 0.11 the return type was changed from
  zip_uint64_t to zip_int64_t. In
  libzip 0.11 the type of flags was changed from
  int to zip_flags_t.