linked list do oddania

#include <stdio.h>
#include <stdlib.h>
#include <ctype.h>
#include <string.h>

typedef struct node{
    char *data;
    struct node *next;
}node;

node* init();y
int length(node* head);
void display(node* head);
void push(node**headPtr, char *data);
void freeList(node** head);
void appendNode(node**headRef, char *data);
node* copy(node* source);
void pop(node**headPtr);
void reverse(node **headPtr);
void sort(node **headPtr);

int main (int argc, char **argv)
{

    node* list = init();
    push(&list, "ONE");
    appendNode(&list, "TWO");
    display(list);
    printf("\n");

    pop(&list);
    reverse(&list);
    node *duplicate = copy(list);
    freeList(&list);
    display(list);
    printf("\n");

    display(duplicate);
    printf("\n");

    sort(&duplicate);
    display(duplicate);

  return(0);
}

node* init()//nitializes empty list, returns pointer to newly created list,
{
    node *head = NULL;
    node *second = NULL;
    node *third = NULL;
    head = malloc(sizeof(node));
    second = malloc(sizeof(node));
    third = malloc(sizeof(node));
    head->data = "AAAAAAAAAA";
    head->next = second;
    second->data ="BBBBBBBB";
    second->next = third;
    third->data = "CCCCCCCCCCC";
    third->next = NULL;
    return head;
}

int length(node* head)// returns number of elements stores on the list identified by parameter
{
    node *currentPosition = head;
    int count = 0;
    while(currentPosition != NULL)
    {
        count++;
        currentPosition = currentPosition->next;
    }
    return count;
}

void display(node* head)//– shows all elements stored on the list identified by a parameter
{
    node *currentPosition = head;
    if(length(head) == 0)
    {
        printf("NO ELEMNETS\n");
    }
    else
    {
    while(currentPosition != NULL)
        {
            printf("%s\n", currentPosition->data);
            currentPosition = currentPosition->next;
        }
    }
}

void push(node**headPtr, char *data)// inserts new element at the beginning on the list identified by paramete
{
    node *newNode = malloc(sizeof(node));
    newNode->data = data;
    newNode->next = *headPtr;
    *headPtr = newNode;
}

void pop(node**headPtr)//removes first element from the end on the list identified by parameter and return storedvalue
{
    node*newNode;
    newNode = *headPtr;
    (*headPtr) = (*headPtr)->next;
    newNode->next = NULL;
    free(newNode);
}

void freeList(node** headPtr)// destroys the list identified by parameter
{
    while(*headPtr)
    {
        freeList(&((*headPtr)->next));
        free(*headPtr);
        *headPtr = NULL;
    }
}

void appendNode(node**headRef, char *data)// to the end of the list insert element
{
    node* currentPosition = *headRef;
    node* newNode;
    newNode = malloc(sizeof(node));
    newNode->data = data;
    newNode->next = NULL;
    if(currentPosition == NULL)
    {
        *headRef = newNode;
    }
    else
    {
        while(currentPosition->next !=NULL)
        {
            currentPosition = currentPosition->next;
        }
        currentPosition->next = newNode;
    }
}

node* copy(node* source)// creates copy of the list identified by parameter
{
    node* head = NULL;
    node** temp = &head;
    while(source)
    {
        *temp = malloc(sizeof(node));
        (*temp)->data = source->data;
        (*temp)->next = NULL;
        source = source->next;
        temp = &((*temp)->next);
    }
    return head;
}

void reverse(node **headPtr)//reverses order of elements of the list identified by parameter
{
    node* currentNode = *headPtr;
    node* previous = NULL;
    node* after = NULL;
    while(currentNode != NULL)
    {
        after = currentNode->next;
        currentNode->next = previous;
        previous = currentNode;
        currentNode = after;
    }
    *headPtr = previous;
}
void sort(node **headPtr)//sort elements of the list identified by parameter
{
    int swapped;
    node*newNode;
    node* lastNode = NULL;

        do
        {
            swapped = 0;
            newNode = *headPtr;
            while(newNode->next != lastNode)
            {
                char* firstString = newNode->data;
                char * secondString = newNode->next->data;
                if(strcmp(firstString,secondString) > 0)
                {
                    char * temporaryString = newNode->data;
                    newNode->data = newNode->next->data;
                    newNode->next->data = temporaryString;
                    swapped = 1;
                }
                newNode = newNode->next;
            }
            lastNode = newNode;
        }
        while(swapped);
    }