void pointers and scanf/printf

have i written this program correctly ?
>
it is giving me correct output but i am little suspicious in the
following two statements -
>
scanf("%d", &ptr->data) and printf("%d\n", ptr->data).
>
/********** LINK LIST **********/
>
#include <stdio.h>
#include <stdlib.h>
>
typedef struct node_s
{
void *data;
struct node_s *next;
>
}node;
>
int add_to_link_list(node **head)
{
node *ptr;
int temp;
>
ptr = malloc(sizeof(node));
>
if (ptr == NULL)
{
fprintf(stderr, "Memory allocation failed\n");
return (1);
}
>
ptr->data = malloc(sizeof(int));
if (ptr->data == NULL)
{
fprintf(stderr, "Memory allocation failed\n");
return (1);
}
>
printf("Enter data\n");
if (scanf("%d", &ptr->data) != 1)
{
fprintf(stderr, "Error while entering data\n");
return (1);
}
>
ptr->next = *head;
*head = ptr;
>
return (0);
>
}
>
int main(void)
{
node *head = NULL;
node *ptr;
int n, i;
>
printf("How many numbers\n");
if (scanf("%d", &n) != 1)
{
fprintf(stderr, "Error while enterning list size\n");
return (EXIT_FAILURE);
}
>
for (i = 0; i < n; i++)
{
if (add_to_link_list(&head))
{
fprintf(stderr, "add_to_link_list failed\n");
return (EXIT_FAILURE);
}
}
>
ptr = head;
>
while (ptr != NULL)
{
printf("%d\n", ptr->data);
ptr = ptr->next;
}
>
return (EXIT_SUCCESS);
>
}

your program don't work, have a segfault, compile with -Wall (if
you're using gcc) and try solve the errors, any doubt post here

On Jul 21, 2:23 am, voidpointer <diegorocha1...@gmail.comwrote:
>>
Hello, Can you please check the first post again ? I have changed the
code. I got no warnings from my dmc/pellesC compilers and the outpu is
correct.

On Jul 20, 6:28 pm, pereges <Brol...@gmail.comwrote:
>>>>
Hello, now work but have one warning message,
>
In function 'add_to_link_list':
test.c:30: warning: format '%d' expects type 'int *', but argument 2
has type 'void *'
>
you can solve this with a cast in your scanf, like this scanf("%d",
(int*)ptr->data)
and you have a lot of memory leak in your code, you doesn't free()d
the allocated space by malloc,
other thing, if you expect work with int, so use int, because void*
can be hard to work,
and need a lot of cast in your code

only a correction, use scanf("%d", (int*)&ptr->data), sorry

On Jul 20, 6:28 pm, pereges <Brol...@gmail.comwrote:>
Hello, now work but have one warning message,
>
In function 'add_to_link_list':
test.c:30: warning: format '%d' expects type 'int *', but argument 2
has type 'void *'

you can solve this with a cast in your scanf, like this scanf("%d",
(int*)ptr->data)

have i written this program correctly ?
>
it is giving me correct output but i am little suspicious in the
following two statements -
>
scanf("%d", &ptr->data) and printf("%d\n", ptr->data).

typedef struct node_s
{
void *data;
struct node_s *next;
>
}node;

On Jul 21, 3:12 am, voidpointer <diegorocha1...@gmail.comwrote:
>>
but ptr->data is already address then why &ptr->data ?

On Jul 21, 3:12 am, voidpointer <diegorocha1...@gmail.comwrote:
>>
but ptr->data is already address then why &ptr->data ?

On Jul 20, 7:15 pm, pereges <Brol...@gmail.comwrote:>
this is only to avoid the warning message.

pereges <Broli00@gmail.comwrites:>
You some problems if you are asking this. I thought you'd written
>
scanf("%d", &ptr->data)
>
because you were knowingly breaking the type rules to put an int into
value into a void * object.
>
Both
>
scanf("%d", ptr->data)
>
and the type-correct version:
>
scanf("%d", (int *)ptr->data)
>
are wrong because they try to use an indeterminate pointer. The data
field has not been set to point anywhere.

On Sun, 20 Jul 2008 23:58:16 +0100, Ben Bacarisse wrote:>
To quote the original message:
>
ptr->data = malloc(sizeof(int));

ptr->data has been properly initialised, so
>
scanf("%d", (int *)ptr->data)
>
is correct.

I had delete the previous code and posted a new code. I don't know how
others can still see the previous code but it happens always with
google and its quite irritating.

pereges said:
>>
Google has nothing to do with it. Usenet is not Google, any more than the
World Wide Web is Internet Explorer, email is Outlook Express, or
spreadsheets are Lotus 1-2-3.
>
When you post a Usenet article, it is sent to a great many servers all over
the world. It used to be pretty easy to cancel messages until that service
got abused. Now, few servers honour cancellation requests - it's a shame,
but it's easy to understand why. Even if Google offers a cancellation
option, the rest of the world is under no obligation to follow suit.