Distributed Systems Network Management (DSNM) Subsystem Interface Development Guide

DSNM Library Services
Distributed Systems Network Management (DSNM) Subsystem Interface Development
Guide—109759 A-75
_NOTNULL
_NOTNULL
_NOTNULL is a Boolean define statement that is TRUE if address is a nonnull extended
memory pointer. TRUE is nonzero, not necessarily -1.
Always use either _NOTNULL or _ISNULL to test a pointer rather than comparing it to
the library literal _NULL. (There are multiple internal values that are accepted as
equivalent to _NULL.)
address input
INT(32)
is the tested extended address.
Example
The following example scans a list forward:
_LIST (list);
INT .EXT lm (list^member^def); !extended pointer to
!list member structure
@lm := _NULL;
WHILE _NOTNULL (@lm := _SUCCESSOR^LM (list,lm)) DO
BEGIN
...! while pointer is not null there are more members on
! the list
END;
_NOTNULL ( address )