hash-table-count hash-table → count

hash-table — a hash table.

count — a non-negative integer.

Returns the number of entries in the hash-table. If hash-table has just been created or newly cleared (see clrhash) the entry count is 0.

(setq table (make-hash-table)) → #<HASH-TABLE EQL 0/120 32115135> 
(hash-table-count table) → 0 
(setf (gethash 57 table) "fifty-seven") → "fifty-seven" 
(hash-table-count table) → 1 
(dotimes (i 100) (setf (gethash i table) i)) → NIL 
(hash-table-count table) → 100

clrhash, remhash, setf of gethash

hash-table-size

The following relationships are functionally correct, although in practice using hash-table-count is probably much faster:

(hash-table-count table) ≡ 
(loop for value being the hash-values of table count t) ≡ 
(let ((total 0)) 
  (maphash #'(lambda (key value) 
               (declare (ignore key value)) 
               (incf total)) 
           table) 
  total)