i'm getting this error... i don't know what to do.. please help...
Code:typedef struct node { int age; struct node *prev; struct node *next; } person; typedef struct node2 { char name[10]; struct node2 *move; } person2; void move(person **a){ //some code... person2 *p; p = (person2 *)malloc(sizeof(person2)); p->move = *a; //this is where the error points at //some code... }
Person and person2 aren't the same type!
You're trying to assign a person (aka node) to a pointer to node2 (aka person2).
And you realize that it's possible to write person** a and person2* p as well?
Originally Posted by Adak
thanks, but, can you please discuss more on solving this problem? i'm still new to C.. sorry..
Well, if someone is expecting an orange, you don't hand them an apple, do you? Likewise, in both C and C++, the left and right side types of an assignment should match.
You must understand that in these low-level languages, the compiler only knows the type by looking at your code. If you assign a person2 where a person is expected, you're going to get problems later (because the compiler will think it's a person2 while it's a person in reality).
do I have to typecast one of the sides?
No, typecasts do not change the underlying type when you cast pointers.
Actually, I see you have two problems...
You try to assign a non-pointer to pointer and try to assign incompatible types.
I strongly suggest you go back to tutorials or books and re-read pointers and whatnot.
> p->move = *a;
OK, so you cast it, make the warning go away and forget it.
Then what happens next?
Sometime later in the code, you're looking at a ptr->move
Are you expecting to find at the other end of it a person or a person2?
If you're expecting to find a person, then declare move as
struct node *move;
Otherwise, think carefully about what it is you're trying to do.
If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
If at first you don't succeed, try writing your phone number on the exam paper.
but, what I want to do is to traverse person2 on person...
what should I do?
Look, this isn't rocket science. Currently, you tell the compiler that person should contain nodes of persons. What do you have to do to change it to person2s?
Do you know how to make flowcharts? Or pseudo code? I suggest you learn them, because it's obvious it's going to benefit you greatly.
I think I got it.. thanks for all the help
Code:typedef struct node2 { char name[10]; struct node *move; //i removed '2' from node } person2;
Are you sure? Have you tried compiling?
You still don't grasp pointers correctly.
Yes.. and it worked perfectly..
Well it's just a part of a HUGE code I'm currently working on..
Again, thanks for all the help..
I'm skeptical, and you are probably causing memory leaks here and there, too.
I think you need to scale down and study pointers more.
I'm busily trying to banish this thread from my memory, in the interests of sleeping tonight. <shudder>.
