🚀 go-pugleaf

In article <990@becker.UUCP> bdb@becker.UUCP (Bruce Becker) writes:
Bruce> Xref: sics.se alt.msdos.programmer:153 comp.sys.ibm.pc:29919

Bruce> In article <565@titan.tsd.arlut.utexas.edu> elrond@titan.tsd.arlut.utexas.edu (Brad Hlista) writes:

Bruce> |far *ptr;

Bruce> |main()

[... unimportant things deleted ...]

Bruce> |	f(i=0;i<1000;i++)
Bruce> |		*(ptr+i)=3.1415927;

Bruce> Should be:	*((float *)(ptr+i)) = 3.1415927;

(* GAACK *) This means you should use the i'th INTEGER location, not float!
Wow. The effect when printing out would be quite a sight...

No, the correct syntax would be : *((float *)ptr + i)

This way, you tell the compiler that ptr really is a float pointer, then
offset the whole thing with i.

In your solution, the offset would be 2*i bytes (2 = sizeof(int)). In mine,
the offset would be 4*i bytes (4=sizeof(float)) !!!!

Bruce> |	for(i=0;i<10;i++)
Bruce> |		printf(" %f", (float) *(ptr+i) ) ;  /* is yielding 3.00000 */

Bruce> Should be	printf(" %f", *((float *)(ptr+i)) ) ;  /* is yielding 3.1415927 */

Likewise here. Use *((float)ptr + i) instead !

Bruce> 	sizeof(far) == sizeof(float); is there a
Bruce> 	"far long" type? Better yet, a "far float"?

Wow. sizeof(far) ! Never seen that before. This would mean 'far int', which is
not (as far as I know) permitted in TC.
far is only applied on pointer and functions, to tell the compiler you need a
4-byte adress to get those objects. Thus, far is a modifier, not a type.
Now, about int. int is the same as short in TC, a 2-byte integer. float is a
4-byte float.

One IMPORTANT rule when you program in C: NEVER assume anything about the size
of differnet types. NEVER !!!!!

Bruce> 	I didn't actually try this so if your compiler
Bruce> 	barfs on "*((float *)ptr)" where "ptr" is a
Bruce> 	"far *" declaration, well... you could try
Bruce> 	"far float * ptr;", etc...

Quite surprising. I just tried it with Turbo C v 2.0, writing 
*((float *)ptr+i), and it worked just nice. writing *((float *)(ptr+i)) gave
me 0.000000 when I tried it...


--
Tommy Levitte 
	gizmo@nada.kth.se
	gizmo@kicki.stacken.kth.se
	gizmo@ttt.kth.se