C program reversed linked list

Question

Im trying to write a program in c that adds big numbers with linked list. I used reverse to add the numbers, but i cant get it to reverse again. It should be used several times(

Answer 1

link list reverse sample like this

#include 
#include 

typedef struct node {
  int digit;
  struct node *next;
} node;

node *reverse_copy(node *list){
    node *new_list = NULL;
    while(list){
        node *new_node = malloc(sizeof(node));
        new_node->digit = list->digit;
        new_node->next = new_list;
        new_list = new_node;
        list = list->next;
    }
    return new_list;
}

void reverse_not_copy(node **header){
    node *tmp, *list, *newList = NULL;
    if (header==NULL || *header == NULL) return;
    list = *header;
    while(list != NULL){
        tmp = list;
        list = list->next;
        tmp->next = newList;
        newList = tmp;
    }
    *header = newList;
}

void print(node *head){
    while(head){
        printf("%d ", head->digit);
        head = head->next;
    }
    printf("\n");
}

int main(void){
    node *np;
    node n[3] = { {1,NULL}, {2, NULL}, {3, NULL}};
    n[0].next = &n[1];
    n[1].next = &n[2];

    print(&n[0]);//1 2 3
    np=reverse_copy(&n[0]);
    print(np);//3 2 1
    reverse_not_copy(&np);
    print(np);//1 2 3
    return 0;
}