NULL ROUTINE POINTERS

[kenny at uiucdcsb.CS.UIUC.EDU]

/* Written  7:08 pm  Nov 27, 1985 by jeff at isi-vaxa.arpa in uiucdcsb:net.lang.c */
/* ---------- "NULL ROUTINE POINTERS" ---------- */
After all the talk about null object pointers on machines with non-zero
null addresses, how would you portably define a null routine pointer?:

Assume that the routine returns a short, -
The following don't seem to work:

#define		NULLROUTINE		((short *()) 0)
#define		NULLROUTINE		((short *) 0())

And:

#define		NULLROUTINE		((short *0)())
or
#define		NULLROUTINE		((short)(*0)())

If all of the above make no sense...Then what?

						Jeff /* End of text from
uiucdcsb:net.lang.c */

To make a cast, write a (fully-parenthesized) declaration of one item of the
desired type, and then take out the name.  So, if you want a pointer to a
function returning short, you might say

short (*pfs) ();

To cast 0 to this type, it's

(short (*) ()) 0;

so

#define NULL_FUNCTION ((short (*) ()) 0)

Kevin
kenny at Uiuc.ARPA	kenny at Uiuc.CSNET
{ihnp4, pur-ee, convex}!uiucdcs!kenny

No opinions are expressed here, so no disclaimer is needed.