dereference problem
Author
I have my Linked List class...
I have my Node structs. They contain a void* pointer to the data.
Now - how do I dereference that?
The code looks like this:
unsigned long Val = (unsigned long)List.Current->Data;
but this is a pointer ---^^^^
And I need to dereference it....?
Anyone - please!?
Author
quote: Original post by SiCrane
If you have
void * data = new long;
Then you can do:
long value = *((long *)data);
Thats great - thanks! But do you know if there is any way to do it in one line? Without the extra declaration...
Edited by - vallis on 3/16/00 6:44:11 PM
Author
quote:Original post by SiCrane
If you have
void * data = new long;
Then you can do:
long value = *((long *)data);
Thats great - thanks! But do you know if there is any way to do it in one line?
Well the type of *((long *)data) is a long, so just use that where ever you need to derefernce your void *.
Alternately you can just macro definition the conversions. ex:
#define DeRefAsLong(x) (*((long *)(x)))
Alternately you can just macro definition the conversions. ex:
#define DeRefAsLong(x) (*((long *)(x)))
Author
Whoooooooosh!
That was the sound of something going way over my head
Would you be so kind as to explain that again for me SiCrane?
TIA!
That was the sound of something going way over my head
Would you be so kind as to explain that again for me SiCrane?
TIA!
Ok you''ve got a void * called data.
(long *)data is a pointer to a long.
*((long *)data) is a dereference of a pointer to a long.
So where ever you need derefernce that void * pointer as a long then you can put *((long *)data).
Alternately you can just create a macro that will take care of the dereferncing for you.
So if you have
#define DeRefAsLong(x) (*((long *)(data)))
Then you can use
long value = DeRefAsLong(data);
Or:
Some_Function_With_Long_Argument(DeRefAsLong(data));
but you can still do:
Some_Function_With_Long_Argument(*((long *)data));
Did that clear it up? Or am I just confusing you further?
(long *)data is a pointer to a long.
*((long *)data) is a dereference of a pointer to a long.
So where ever you need derefernce that void * pointer as a long then you can put *((long *)data).
Alternately you can just create a macro that will take care of the dereferncing for you.
So if you have
#define DeRefAsLong(x) (*((long *)(data)))
Then you can use
long value = DeRefAsLong(data);
Or:
Some_Function_With_Long_Argument(DeRefAsLong(data));
but you can still do:
Some_Function_With_Long_Argument(*((long *)data));
Did that clear it up? Or am I just confusing you further?
Looks good, but as paranoia I always wrap both sides of a cast in paranthesis. i.e.
*((unsigned long *)(List.Current->Data))
rathar than
*((unsigned long *)List.Current->Data)
I just think it''s easier to read.
*((unsigned long *)(List.Current->Data))
rathar than
*((unsigned long *)List.Current->Data)
I just think it''s easier to read.
This topic is closed to new replies.
Advertisement
Popular Topics
Advertisement
