linked list help needed

[john2020]

I need to allocate a block of 256 bytes and insert into the first node linked list and free block from linked list.

 

[horace1]

I need to allocate a block of 256 bytes and insert into the first node linked list and free block from linked list.

what language are you using?
if C++ you have a number of container classes including <list>

 

[john2020]

I use c language. I am not aware of container classes. here is what i wrote so far...can u help me?

//insert a node into a linked list
struct node *pNew;
pNew = (struct node *) malloc(sizeof(struct node));
pNew -> data = item;
if (pPre == NULL){
//add before first logical node or to an empty list
pNew -> next = pHead;
pHead = pNew;
}
else {
//add in the middle or at the end
pNew -> next = pPre -> next;
pPre -> next = pNew;
}

 

[horace1]

have a look at the examples on CodeProject
https://www.codeproject.com/Articles/24684/How-to-create-Linked-list-using-C-C

https://www.codeproject.com/Articles/668818/Implementing-a-Doubly-Linked-List-to-be-used-on-an

 

[john2020]

please review this code and tell me if approach is correct? I am still not clear as to how to create new block of same size and add to exisitng list.also do i need to add node at the tail of the block?

#include <stdio.h> /* for printf */

#include <stdlib.h> /* for malloc */



struct node

{

int data;

struct node *next; /* pointer to next element in list */

};



struct node *list_add(struct node **p, int i)

{

struct node *n = malloc(sizeof(struct node));

if (n == NULL)

return NULL;



n->next = *p; /* the previous element (*p) now becomes the "next" element */

*p = n; /* add new empty element to the front (head) of the list */

n->data = i;



return *p;

}



void list_remove(struct node **p) /* remove head */

{

if (*p != NULL)

{

struct node *n = *p;

*p = (*p)->next;

free;

}

}

int main(void)

{

struct node *n = NULL;



list_add(&n, 0); /* list: 0 */

list_add(&n, 1); /* list: 1 0 */


return 0;

}

have a look at the examples on CodeProject
https://www.codeproject.com/Articles/24684/How-to-create-Linked-list-using-C-C

https://www.codeproject.com/Articles/668818/Implementing-a-Doubly-Linked-List-to-be-used-on-an