NNUULLLL -- Manifest Constant

The manifest  constant NNUULLLL is defined  in the header file  ssttddddeeff.hh. It is
the  null  pointer (cchhaarr  *)00,  which  is a  pointer  initialized to  zero.
Numerous routines return this value to  indicate failure; it is useful as a
return value  because it points nowhere, and so  removes the possibility of
accidentally destroying a section of memory after failure.

_S_e_e _A_l_s_o
mmaanniiffeesstt ccoonnssttaanntt, NNUULL, ppooiinntteerr, ssttddiioo.hh
ANSI Standard, section 7.1.6
