Week 11 Tutorial Sample Answers

Programming linked lists with multi file systems

Given the starter code:

Question: What is the compilation command for the above multi file system?

dcc -o linked_lists main.c linked_lists.c

we will implement functions to create a node, insert a node at the tail of a linked list, insert a node at the head of a linked list and find the length of a linked list.

linked_lists.h 

// linked_lists.h
// This program was written by Sofia De Bellis (z5418801), on March 2024
// Header file for simple linked lists functions

struct node {
    // The data stored in the node
    int data;
    // Pointer to the next node in the linked list
    struct node *next;
};

// Creates a new node
//
// Parameters:
//      data: The data to be stored in the new node
//
// Returns:
//      A pointer to the new node
struct node *create_node(int data);

// Inserts a new node at the head of a linked list
//
// Parameters:
//      head: A pointer to the head of the linked list
//      data: The data to be stored in the new node
//
// Returns:
//      A pointer to the new head of the linked list
struct node *insert_head(struct node *head, int data);

// Inserts a new node at the tail of a linked list
//
// Parameters:
//      head: A pointer to the head of the linked list
//      data: The data to be stored in the new node
//
// Returns:
//      A pointer to the head of the linked list
struct node *insert_tail(struct node *head, int data);

// Traverses a linked list and prints the data in each node
//
// Parameters:
//      head: A pointer to the head of the linked list
//
// Returns:
//      None
void print_list(struct node *head);

// Finds the number of nodes in a linked list
//
// Parameters:
//      head: A pointer to the head of the linked list
//
// Returns:
//      The number of nodes in the linked list
int list_length(struct node *head);

linked_lists.c 

// linked_list.c
// This program was written by YOUR-NAME (zID)
// Implementation for simple linked lists functions

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

#include "linked_lists.h"

struct node *create_node(int data) {
    // TODO
    exit(1);
}

struct node *insert_head(struct node *head, int data) {
    // TODO
    exit(1);
}

struct node *insert_tail(struct node *head, int data) {
    // TODO
    exit(1);
}

void print_list(struct node *head) {
    // Set current to be the first node in the list
    struct node *current = head;
    
    // Traverse the linked list and print each node 
    // until we reach the end of the list
    while (current != NULL) {
        printf("%d -> ", current->data);
        current = current->next;
    }
    printf("X\n");
}

int list_length(struct node *head) {
    // TODO
    exit(1);
}

main.c

// main.c
// This program was written by YOUR-NAME (zID)
// // Program to test linked lists functions

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

#include "linked_lists.h"

int main(void) {

    // Create a pointer to the head of the linked list
    struct node *head = NULL;

    // Insert a node at the beginning of the linked list
    head = insert_head(head, 10);

    // Insert a node at the beginning of the linked list
    head = insert_head(head, 5);

    // Insert a node at the end of the linked list
    head = insert_tail(head, 15);

    // Insert a node at the end of the linked list
    head = insert_tail(head, 20);

    // Print the linked list
    print_list(head);

    // Calculate and print the length of the linked list
    int length = list_length(head);
    printf("There are %d nodes in the list\n", length);

    return 0;
}