Re: Problem with Generic Pointers

From:

red floyd <no.spam@here.dude>

Newsgroups:

comp.lang.c++,comp.lang.c,comp.lang.c

Date:

Fri, 02 Jun 2006 20:16:56 GMT

Message-ID:

<Y01gg.33822$fb2.17495@newssvr27.news.prodigy.net>

codergem@gmail.com wrote:

Victor Bazarov wrote:

codergem@gmail.com wrote:

I was trying to implement linked list in which the data field is
Generic...
the structure details are..

typedef struct node
{
void *data;
struct node *next;
}gnode;

Now to add a node into it, and i have written this function.

void insert(gnode **head,void *data,unsigned int size)
{
gnode *temp;
int i=0;
temp=(gnode *)malloc(sizeof(gnode));
temp->data=malloc(size);
for(int i=0;i<size;i++)
*(char *)(temp->data+i) = *(char *)(data + i);

temp->next= (*head);
(*head)=temp;
}

Why are you programming in C? Who is teaching you that?

Well i dont know how to copy the data into the temp->data.

Use memcpy.

But I have written the following code...

for(int i=0;i<size;i++)
*(char *)(temp->data+i) = *(char *)(data + i);

But it is giving the error : ' void * ' : Unknown size .

Of course. Drop the casts. Use memcpy.

If anyone knows any other way of copying it please tell me. And please
help me out in finding what is happening wrong in this code.

Please get yourself a good book on C++ and learn it. What you have
here is C (and not C++). It cannot be "fixed" to become C++, you are
much better off rewriting it in C++.

Thanks .

> But I was looking for a way to do it using some logic, without using
> any memcpy function.
> Could you please help me in rectifying that error,but still using that
> logic only.
> Thanks in advance.
>

1. Reply moved to the bottom (Top posting is frowned upon in c.l.c++).
2. Why do you want to avoid memcpy? It's probably going to be better
than anything you can write on your own, as the compiler vendor knows
what's going on internally, while you don't.
3. As Victor said, your code is C. You've posted to comp.lang.c++.
4. If you're going to write C and use C-style malloc, then don't cast
the result from malloc, it can mask an error from a missing #include file.
5. Crossposted to comp.lang.c, followup set to comp.lang.c, since this
is apparently C code.