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0x12-singly_linked_lists

README.md

0x12. C - Singly linked lists

  • By Julien Barbier

Concepts

For this project, students are expected to look at this concept:

Resources

Read or watch:

Learning Objectives

At the end of this project, you are expected to be able to explain to anyone, without the help of Google:

General

  • When and why using linked lists vs arrays
  • How to build and use linked lists

Requirements

General

  • Allowed editors: vi, vim, emacs
  • All your files will be compiled on Ubuntu 20.04 LTS using gcc, using the options -Wall -Werror -Wextra -pedantic -std=gnu89
  • All your files should end with a new line
  • A README.md file, at the root of the folder of the project is mandatory
  • Your code should use the Betty style. It will be checked using betty-style.pl and betty-doc.pl
  • You are not allowed to use global variables
  • No more than 5 functions per file
  • The only C standard library functions allowed are malloc, free and exit. Any use of functions like printf, puts, calloc, realloc etc... is forbidden
  • You are allowed to use _putchar
  • You don't have to push _putchar.c, we will use our file. If you do it won't be taken into account
  • In the following examples, the main.c files are shown as examples. You can use them to test your functions, but you don't have to push them to your repo (if you do we won't take them into account). We will use our own main.c files at compilation. Our main.c files might be different from the one shown in the examples
  • The prototypes of all your functions and the prototype of the function _putchar should be included in your header file called lists.h
  • Don't forget to push your header file
  • All your header files should be include guarded

More Info

Please use this data structure for this project:

/**
 * struct list_s - singly linked list
 * @str: string - (malloc'ed string)
 * @len: length of the string
 * @next: points to the next node
 *
 * Description: singly linked list node structure
 */
typedef struct list_s
{
    char *str;
    unsigned int len;
    struct list_s *next;
} list_t;

Tasks

0. Print list

mandatory

Write a function that prints all the elements of a list_t list.

  • Prototype: size_t print_list(const list_t *h);
  • Return: the number of nodes
  • Format: see example
  • If str is NULL, print [0] (nil)
  • You are allowed to use printf
julien@ubuntu:~/0x12. Singly linked lists$ cat 0-main.c
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "lists.h"

/**
 * main - check the code
 *
 * Return: Always 0.
 */
int main(void)
{
    list_t *head;
    list_t *new;
    list_t hello = {"World", 5, NULL};
    size_t n;

    head = &hello;
    new = malloc(sizeof(list_t));
    if (new == NULL)
    {
        printf("Error\n");
        return (1);
    }
    new->str = strdup("Hello");
    new->len = 5;
    new->next = head;
    head = new;
    n = print_list(head);
    printf("-> %lu elements\n", n);

    printf("\n");
    free(new->str);
    new->str = NULL;
    n = print_list(head);
    printf("-> %lu elements\n", n);

    free(new);
    return (0);
}
julien@ubuntu:~/0x12. Singly linked lists$ gcc -Wall -pedantic -Werror -Wextra -std=gnu89 0-main.c 0-print_list.c -o a
julien@ubuntu:~/0x12. Singly linked lists$ ./a
[5] Hello
[5] World
-> 2 elements

[0] (nil)
[5] World
-> 2 elements
julien@ubuntu:~/0x12. Singly linked lists$

Repo:

  • GitHub repository: alx-low_level_programming
  • Directory: 0x12-singly_linked_lists
  • File: 0-print_list.c

1. List length

mandatory

Write a function that returns the number of elements in a linked list_t list.

  • Prototype: size_t list_len(const list_t *h);
julien@ubuntu:~/0x12. Singly linked lists$ cat 1-main.c
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "lists.h"

/**
 * main - check the code
 *
 * Return: Always 0.
 */
int main(void)
{
    list_t *head;
    list_t *new;
    list_t hello = {"World", 5, NULL};
    size_t n;

    head = &hello;
    new = malloc(sizeof(list_t));
    if (new == NULL)
    {
        printf("Error\n");
        return (1);
    }
    new->str = strdup("Hello");
    new->len = 5;
    new->next = head;
    head = new;
    n = list_len(head);
    printf("-> %lu elements\n", n);
    free(new->str);
    free(new);
    return (0);
}
julien@ubuntu:~/0x12. Singly linked lists$ gcc -Wall -pedantic -Werror -Wextra -std=gnu89 1-main.c 1-list_len.c -o b
julien@ubuntu:~/0x12. Singly linked lists$ ./b
-> 2 elements
julien@ubuntu:~/0x12. Singly linked lists$

Repo:

  • GitHub repository: alx-low_level_programming
  • Directory: 0x12-singly_linked_lists
  • File: 1-list_len.c

2. Add node

mandatory

Write a function that adds a new node at the beginning of a list_t list.

  • Prototype: list_t *add_node(list_t **head, const char *str);
  • Return: the address of the new element, or NULL if it failed
  • str needs to be duplicated
  • You are allowed to use strdup
julien@ubuntu:~/0x12. Singly linked lists$ cat 2-main.c
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "lists.h"

/**
 * main - check the code
 *
 * Return: Always 0.
 */
int main(void)
{
    list_t *head;

    head = NULL;
    add_node(&head, "Alexandro");
    add_node(&head, "Asaia");
    add_node(&head, "Augustin");
    add_node(&head, "Bennett");
    add_node(&head, "Bilal");
    add_node(&head, "Chandler");
    add_node(&head, "Damian");
    add_node(&head, "Daniel");
    add_node(&head, "Dora");
    add_node(&head, "Electra");
    add_node(&head, "Gloria");
    add_node(&head, "Joe");
    add_node(&head, "John");
    add_node(&head, "John");
    add_node(&head, "Josquin");
    add_node(&head, "Kris");
    add_node(&head, "Marine");
    add_node(&head, "Mason");
    add_node(&head, "Praylin");
    add_node(&head, "Rick");
    add_node(&head, "Rick");
    add_node(&head, "Rona");
    add_node(&head, "Siphan");
    add_node(&head, "Sravanthi");
    add_node(&head, "Steven");
    add_node(&head, "Tasneem");
    add_node(&head, "William");
    add_node(&head, "Zee");
    print_list(head);
    return (0);
}
julien@ubuntu:~/0x12. Singly linked lists$ gcc -Wall -pedantic -Werror -Wextra -std=gnu89 2-main.c 2-add_node.c 0-print_list.c -o c
julien@ubuntu:~/0x12. Singly linked lists$ ./c
[3] Zee
[7] William
[7] Tasneem
[6] Steven
[9] Sravanthi
[6] Siphan
[4] Rona
[4] Rick
[4] Rick
[7] Praylin
[5] Mason
[6] Marine
[4] Kris
[7] Josquin
[4] John
[4] John
[3] Joe
[6] Gloria
[7] Electra
[4] Dora
[6] Daniel
[6] Damian
[8] Chandler
[5] Bilal
[7] Bennett
[8] Augustin
[5] Asaia
[9] Alexandro
julien@ubuntu:~/0x12. Singly linked lists$

Repo:

  • GitHub repository: alx-low_level_programming
  • Directory: 0x12-singly_linked_lists
  • File: 2-add_node.c

3. Add node at the end

mandatory

Write a function that adds a new node at the end of a list_t list.

  • Prototype: list_t *add_node_end(list_t **head, const char *str);
  • Return: the address of the new element, or NULL if it failed
  • str needs to be duplicated
  • You are allowed to use strdup
julien@ubuntu:~/0x12. Singly linked lists$ cat 3-main.c
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "lists.h"

/**
 * main - check the code
 *
 * Return: Always 0.
 */
int main(void)
{
    list_t *head;

    head = NULL;
    add_node_end(&head, "Anne");
    add_node_end(&head, "Colton");
    add_node_end(&head, "Corbin");
    add_node_end(&head, "Daniel");
    add_node_end(&head, "Danton");
    add_node_end(&head, "David");
    add_node_end(&head, "Gary");
    add_node_end(&head, "Holden");
    add_node_end(&head, "Ian");
    add_node_end(&head, "Ian");
    add_node_end(&head, "Jay");
    add_node_end(&head, "Jennie");
    add_node_end(&head, "Jimmy");
    add_node_end(&head, "Justin");
    add_node_end(&head, "Kalson");
    add_node_end(&head, "Kina");
    add_node_end(&head, "Matthew");
    add_node_end(&head, "Max");
    add_node_end(&head, "Michael");
    add_node_end(&head, "Ntuj");
    add_node_end(&head, "Philip");
    add_node_end(&head, "Richard");
    add_node_end(&head, "Samantha");
    add_node_end(&head, "Stuart");
    add_node_end(&head, "Swati");
    add_node_end(&head, "Timothy");
    add_node_end(&head, "Victor");
    add_node_end(&head, "Walton");
    print_list(head);
    return (0);
}
julien@ubuntu:~/0x12. Singly linked lists$ gcc -Wall -pedantic -Werror -Wextra -std=gnu89 3-main.c 3-add_node_end.c 0-print_list.c -o d
julien@ubuntu:~/0x12. Singly linked lists$ ./d
[4] Anne
[6] Colton
[6] Corbin
[6] Daniel
[6] Danton
[5] David
[4] Gary
[6] Holden
[3] Ian
[3] Ian
[3] Jay
[6] Jennie
[5] Jimmy
[6] Justin
[6] Kalson
[4] Kina
[7] Matthew
[3] Max
[7] Michael
[4] Ntuj
[6] Philip
[7] Richard
[8] Samantha
[6] Stuart
[5] Swati
[7] Timothy
[6] Victor
[6] Walton
julien@ubuntu:~/0x12. Singly linked lists$

Repo:

  • GitHub repository: alx-low_level_programming
  • Directory: 0x12-singly_linked_lists
  • File: 3-add_node_end.c

4. Free list

mandatory

Write a function that frees a list_t list.

  • Prototype: void free_list(list_t *head);
julien@ubuntu:~/0x12. Singly linked lists$ cat 4-main.c
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "lists.h"

/**
 * main - check the code
 *
 * Return: Always 0.
 */
int main(void)
{
    list_t *head;

    head = NULL;
    add_node_end(&head, "Bob");
    add_node_end(&head, "&");
    add_node_end(&head, "Kris");
    add_node_end(&head, "love");
    add_node_end(&head, "asm");
    print_list(head);
    free_list(head);
    head = NULL;
    return (0);
}
julien@ubuntu:~/0x12. Singly linked lists$ gcc -Wall -pedantic -Werror -Wextra -std=gnu89 4-main.c 4-free_list.c 3-add_node_end.c 0-print_list.c -o e
julien@ubuntu:~/0x12. Singly linked lists$ valgrind ./e
==3598== Memcheck, a memory error detector
==3598== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==3598== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==3598== Command: ./e
==3598==
[6] Bob
[1] &
[3] Kris
[4] love
[3] asm
==3598==
==3598== HEAP SUMMARY:
==3598==     in use at exit: 0 bytes in 0 blocks
==3598==   total heap usage: 11 allocs, 11 frees, 1,166 bytes allocated
==3598==
==3598== All heap blocks were freed -- no leaks are possible
==3598==
==3598== For counts of detected and suppressed errors, rerun with: -v
==3598== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
julien@ubuntu:~/0x12. Singly linked lists$

Repo:

  • GitHub repository: alx-low_level_programming
  • Directory: 0x12-singly_linked_lists
  • File: 4-free_list.c

5. The Hare and the Tortoise

#advanced

Write a function that prints You're beat! and yet, you must allow,\nI bore my house upon my back!\n before the main function is executed.

  • You are allowed to use the printf function
julien@ubuntu:~/0x12. Singly linked lists$ cat 100-main.c
#include <stdio.h>

/**
 * main - check the code
 *
 * Return: Always 0.
 */
int main(void)
{
    printf("(A tortoise, having pretty good sense of a hare's nature, challenges one to a race.)\n");
    return (0);
}
julien@ubuntu:~/$ gcc -Wall -pedantic -Werror -Wextra -std=gnu89 100-main.c 100-first.c -o first
julien@ubuntu:~/$ ./first
You're beat! and yet, you must allow,
I bore my house upon my back!
(A tortoise, having pretty good sense of a hare's nature, challenges one to a race.)
julien@ubuntu:~/$

Repo:

  • GitHub repository: alx-low_level_programming
  • Directory: 0x12-singly_linked_lists
  • File: 100-first.c

6. Real programmers can write assembly code in any language

#advanced

Write a 64-bit program in assembly that prints Hello, Holberton, followed by a new line.

  • You are only allowed to use the printf function
  • You are not allowed to use interrupts
  • Your program will be compiled using nasm and gcc:
julien@ubuntu:~/$ nasm -f elf64 101-hello_holberton.asm && gcc -no-pie -std=gnu89 101-hello_holberton.o -o hello
julien@ubuntu:~/$ ./hello
Hello, Holberton
julien@ubuntu:~/$

Repo:

  • GitHub repository: alx-low_level_programming
  • Directory: 0x12-singly_linked_lists
  • File: 101-hello_holberton.asm