i have an array, i want to create a doubly linked list from it,by transferring my elements to the nodes. and linking them through pointers(prev and next) what i did was
head = malloc(sizeof(struct)) head->prev=NULL head->next=NULL tail=head
for(i=0;i<num;i++){
//copy data from arr[i] to tail
temp=tail
tail->next=malloc(sizeof(struct))
tail=tail->next
tail->prev=temp
}
now, how do i copy the data? temp, head and tail are pointers to structure
I guess you did not try writing and compiling. The elements of linked list should have at least some place to hold value from your array, let's say data of int type.
#include <stdio.h>
#include <malloc.h>
#define N 3
typedef struct a{
struct a* prev;
struct a* next;
int data;
}item;
int main(void)
{
item* head;
item* tail;
item* temp;
int num = N;
int data[N] = {1,2,3}; /*initialization*/
int i = 0;
head = (item*)malloc(sizeof(item));
head -> prev = NULL;
head -> next = NULL;
tail = head;
for(i = 0; i < num; i ++){
temp = tail;
tail -> next = (item*)malloc(sizeof(item));
tail = tail -> next;
tail -> next = NULL;
tail -> data = data[i];
tail -> prev = temp;
}
for(temp = head -> next; temp != NULL; temp = temp -> next) /*the following is for testing purpose*/
printf("%d\t", temp -> data);
return 0;
}
Be aware that the head element does not contain what you want.
create temp node and parse linklist from to last node assign these detail
counter=start_node;
temp=(struct NODE *)malloc(sizeof(struct NODE)); /*create new node*/
temp->node_data=data; /*set data in new node*/
while(counter -> next_node!=NULL)
{
counter=counter->next_node; /*increment in counter*/
}
temp->prev_node=counter; /*set next node of new node*/
counter->next_node = temp;
temp->next_node = null;
here temp is the current node.
You need to save tail->prev, so you can do:
node * tailPrev = tail->prev;
memcpy(tail, &arr[i], sizeof(*tail));
tail->prev = tailPrev;
//continue with your code...
memcpy, but it's hard to tell what your problem is. You only say what you want to do, but not why you fail at doing so. And again, the code you posted is not valid C, so it's either not exactly what you did, or that may be your problem because you can't compile.