18.2.4 hash-table-count [Function]

hash-table-count hash-table ⇒ count

Arguments and Values::

hash-table—a hash table.

count—a non-negative integer.

Description::

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.

Examples::

 (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

Affected By::

clrhash, remhash, setf of gethash

See Also::

hash-table-size

Notes::

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)