nullp

       nullp()  -  determine  whether  or not a given variable is
       null.

SYNOPSIS

       int nullp( mixed arg );

DESCRIPTION

       Return 1 if `arg' is null.  'arg' will be null in the fol-
       lowing cases:

       1.     it has not yet been initialized.

       2.     it points to a destructed object.

       3.     it  is  a  function  (formal) parameter that corre-
              sponds to a missing actual argument.

SEE ALSO

       mapp(3),  stringp(3),  pointerp(3),  objectp(3),  intp(3),
       bufferp(3),    floatp(3),   functionp(3),   undefinedp(3),
       errorp(3)