i have to use malloc?

[rolfjf]

I need to create a simple linked list, with 16 elements.
The struct is:

struct processo {
int pid;
struct processo *prox;
};

I need to create a list, with a pointer poiting to the first element, and the elements have the values 0-15.
How do I create the list?
I have to use malloc to allocate all the elements, with a for?
I tried to do this without malloc, and it doesn't work.
When I try to access the first element, it returns not the value 0, that it sould...
Can someone help me with the creation of this list?
thank you.
Rolf

 

[rbobbitt]

Yes, you need to use malloc or one of its friends. To create the list initially, something like this:

#include <stdlib.h>

/* ... */

struct processo *
createList(int pid)
{
struct processo *list=malloc(sizeof *list);

if (list!=NULL) {
list->pid=pid;
list->prox=NULL;
}
return list;
}

To add an item to the back of the list, you just have to iterate through the list to the end and attach the item once the next item is NULL:

int
appendItem(struct processo *list,int pid)
{
struct processo *idx;
int error=0;

/* Create the new item */
struct processo *item=createList(pid);

if (NULL==item) {
error=1; /* couldn't get memory */
} else {
/* Advance to the end of the list */
for (idx=list;idx->prox!=NULL;idx=idx->prox)
; /* Empty loop */
/* Attach the new item */
idx->prox=item;
}
return error;
}

I'll leave it to you put it together so that it matches your specs.

Russ
bobbitts@hotmail.com

http://home.earthlink.net/~bobbitts

 

[SwapSawe]

Ofcourse to create Linked list u'll have to use malloc;

struct emp {
char *emp;
int age;
struct *next_record;
}
//Adding Records
main()
{
continue = 'y';
struct emp *start, // for keeping track of BOF
*current; //for keeping track of current record referred.

*start = (struct emp *) malloc(sizeof(struct emp));
current = start;

while(current != NULL)
{
//accept data

printf(&quot;Want to continue >>&quot;
continue = getche();
if(continue == 'Y' || continue == 'y')
{
current->next = (struct emp*) malloc(sizeof(struct emp));
current = current->next;
}
else
{
current->next = null;
current = current->next;
}
}


I hope the code is not very tough to understand

Regards,
SwapSawe.

 

[rbobbitt]

It doesn't compile:

$ gcc -W -Wall foo.c
foo.c:4: parse error before `*'
foo.c:4: warning: no semicolon at end of struct or union
foo.c:8: warning: return-type defaults to `int'
foo.c: In function `main':
foo.c:9: parse error before `='
foo.c:13: dereferencing pointer to incomplete type
foo.c:13: warning: implicit declaration of function `malloc'
foo.c:13: sizeof applied to an incomplete type
foo.c:16: `NULL' undeclared (first use in this function)
foo.c:16: (Each undeclared identifier is reported only once
foo.c:16: for each function it appears in.)
foo.c:20: warning: implicit declaration of function `printf'
foo.c:21: parse error before `='
foo.c:22: parse error before `continue'
foo.c:25: dereferencing pointer to incomplete type
foo.c:27: parse error before `else'
foo.c:30: dereferencing pointer to incomplete type
foo.c:31: warning: control reaches end of non-void function
foo.c: At top level:
foo.c:32: parse error before `}'


Russ
bobbitts@hotmail.com

http://home.earthlink.net/~bobbitts