zip_file_extra_fields_count,
    zip_file_extra_fields_count_by_id —
    count extra fields for file in zip
#include
  <zip.h>
zip_int16_t
  
  zip_file_extra_fields_count(zip_t
    *archive, zip_uint64_t
    index, zip_flags_t
    flags);
zip_int16_t
  
  zip_file_extra_fields_count_by_id(zip_t
    *archive, zip_uint64_t
    index, zip_uint16_t
    extra_field_id,
    zip_flags_t flags);
The
    ()
    function counts the extra fields for the file at position
    index in the zip archive.
The following flags are supported:
  ZIP_FL_CENTRAL 
  - Count extra fields from the archive's central directory.
 
  ZIP_FL_LOCAL 
  - Count extra fields from the local file headers.
 
  ZIP_FL_UNCHANGED 
  - Count the original unchanged extra fields, ignoring any changes made.
 
 
Extra fields that are the same in the central directory and the
    local file header are merged into one. Therefore, the counts with
    ZIP_FL_CENTRAL and
    ZIP_FL_LOCAL do not need to add up to the same value
    as when given ZIP_FL_CENTRAL|ZIP_FL_LOCAL at the
    same time.
Upon successful completion, the requested number of extra fields
    is returned. Otherwise, -1 is returned and the error code in
    archive is set to indicate the error.
zip_file_extra_fields_count() and
    zip_file_extra_fields_count_by_id() fail if:
  - [
ZIP_ER_NOENT] 
  - index is not a valid file index in
      archive.
 
zip_file_extra_fields_count() and
    zip_file_extra_fields_count_by_id() were added in
    libzip 0.11.