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From: vander@nssdcb.gsfc.nasa.gov (John Vanderpool)
Newsgroups: comp.lang.c,comp.os.vms
Subject: question about free()
Message-ID: <2958@dftsrv.gsfc.nasa.gov>
Date: 31 Jul 90 21:40:29 GMT
Sender: news@dftsrv.gsfc.nasa.gov
Reply-To: vander@nssdcb.gsfc.nasa.gov
Organization: NASA - Goddard Space Flight Center
Lines: 55
News-Software: VAX/VMS VNEWS 1.3-4

does the free() function return anything?
in VAXC v3.0 it's defined as:  void free (void *ptr);

i though it used to (just to tell you it was successful)
  - was that an incorrect implementation ?

if the argument is void *ptr how does it know how many bytes to release?
which brings me to my example (attached) do i need to cast the pointer
before free()ing it?

thanx, hope this isn't too stupid!

				fish

------------------------------------------------------------------------------

/* each type of XAB is a different size structure on VAX/VMS for unix folks */

#include xab

#define NULL (void *) 0


void RMS_free_XABchain( struct XABKEY *xabp )

	/* originally had as void *xabp but then you can't reference its
			elements */
{

	/* cast XAB pointer using XAB type code in xab$b_cod */

	switch( xabp->xab$b_cod )
	{
	  case XAB$C_ALL : xabp = (struct XABALL *) xabp;  break;
	  case XAB$C_DAT : xabp = (struct XABDAT *) xabp;  break;
	  case XAB$C_FHC : xabp = (struct XABFHC *) xabp;  break;
	  case XAB$C_KEY : xabp = (struct XABKEY *) xabp;  break;
	  case XAB$C_PRO : xabp = (struct XABPRO *) xabp;  break;
	  case XAB$C_RDT : xabp = (struct XABRDT *) xabp;  break;
	  case XAB$C_SUM : xabp = (struct XABSUM *) xabp;  break;
	  case XAB$C_TRM : xabp = (struct XABTRM *) xabp;  break;
	  default : printf( "bad xab code=%d\n", xabp->xab$b_cod );  return;

	}	/* end switch */


	/* recursively call until end of chain is reached, free on unwind */

	if( xabp != NULL )
	{
	  RMS_free_XABchain( xabp->xab$l_nxt );
	  free( xabp );
	}

}	/* RMS_free_XAB_chain */