Name: sslength

Syntax:
(sslength ss)

Description:
Returns the total number of entities contained in the selection set.

Example(s):
(setq SS_NEW (ssget))
(if (/= SS_NEW nil)
  (progn
    (setq CNT (itoa (sslength SS_NEW)))
    (prompt (strcat "\n" CNT " objects"))
  )
)