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README.md

0x13-more_singly_linked_lists Project

Learning Objectives

  • How to use linked lists
  • Start to look for the right source of information without too much help

Tasks

Print list

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

  • Prototype: size_t print_listint(const listint_t *h);
  • Return: the number of nodes
  • Format: see example
  • You are allowed to use printf

Solution: 0-print_listint.c

$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ cat 0-main.c 
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "lists.h"

/**
 * main - check the code for Holberton School students.
 *
 * Return: Always 0.
 */
int main(void)
{
    listint_t *head;
    listint_t *new;
    listint_t hello = {8, NULL};
    size_t n;

    head = &hello;
    new = malloc(sizeof(listint_t));
    if (new == NULL)
    {
        printf("Error\n");
        return (1);
    }
    new->n = 9;
    new->next = head;
    head = new;
    n = print_listint(head);
    printf("-> %lu elements\n", n);
    free(new);
    return (0);
}
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ gcc -Wall -pedantic -Werror -Wextra 0-main.c 0-print_listint.c -o a
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ ./a 
9
8
-> 2 elements
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$

List length

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

  • Prototype: size_t listint_len(const listint_t *h);

Solution: 1-listint_len.c

$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ cat 1-main.c 
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "lists.h"

/**
 * main - check the code for Holberton School students.
 *
 * Return: Always 0.
 */
int main(void)
{
    listint_t *head;
    listint_t *new;
    listint_t hello = {8, NULL};
    size_t n;

    head = &hello;
    new = malloc(sizeof(listint_t));
    if (new == NULL)
    {
        printf("Error\n");
        return (1);
    }
    new->n = 9;
    new->next = head;
    head = new;
    n = listint_len(head);
    printf("-> %lu elements\n", n);
    free(new);
    return (0);
}
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ gcc -Wall -pedantic -Werror -Wextra 1-main.c 1-listint_len.c -o b
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ ./b 
-> 2 elements
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$

Add node

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

  • Prototype: listint_t *add_nodeint(listint_t **head, const int n);
  • Return: the address of the new element, or NULL if it failed

Solution: 2-add_nodeint.c

$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ cat 2-main.c 
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "lists.h"

/**
 * main - check the code for Holberton School students.
 *
 * Return: Always 0.
 */
int main(void)
{
    listint_t *head;

    head = NULL;
    add_nodeint(&head, 0);
    add_nodeint(&head, 1);
    add_nodeint(&head, 2);
    add_nodeint(&head, 3);
    add_nodeint(&head, 4);
    add_nodeint(&head, 98);
    add_nodeint(&head, 402);
    add_nodeint(&head, 1024);
    print_listint(head);
    return (0);
}
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ gcc -Wall -pedantic -Werror -Wextra 2-main.c 2-add_nodeint.c 0-print_listint.c -o c
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ ./c 
1024
402
98
4
3
2
1
0
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$

Add node at the end

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

  • Prototype: listint_t *add_nodeint_end(listint_t **head, const int n);
  • Return: the address of the new element, or NULL if it failed

Solution: 3-add_nodeint_end.c

$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ cat 3-main.c 
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "lists.h"

/**
 * main - check the code for Holberton School students.
 *
 * Return: Always 0.
 */
int main(void)
{
    listint_t *head;

    head = NULL;
    add_nodeint_end(&head, 0);
    add_nodeint_end(&head, 1);
    add_nodeint_end(&head, 2);
    add_nodeint_end(&head, 3);
    add_nodeint_end(&head, 4);
    add_nodeint_end(&head, 98);
    add_nodeint_end(&head, 402);
    add_nodeint_end(&head, 1024);
    print_listint(head);
    return (0);
}
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ gcc -Wall -pedantic -Werror -Wextra 3-main.c 3-add_nodeint_end.c 0-print_listint.c -o d
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ ./d 
0
1
2
3
4
98
402
1024
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$

Free list

Write a function that frees a listint_t list.

  • Prototype: void free_listint(listint_t *head);

Solution: 4-free_listint.c

$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ cat 4-main.c 
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "lists.h"

/**
 * main - check the code for Holberton School students.
 *
 * Return: Always 0.
 */
int main(void)
{
    listint_t *head;

    head = NULL;
    add_nodeint_end(&head, 0);
    add_nodeint_end(&head, 1);
    add_nodeint_end(&head, 2);
    add_nodeint_end(&head, 3);
    add_nodeint_end(&head, 4);
    add_nodeint_end(&head, 98);
    add_nodeint_end(&head, 402);
    add_nodeint_end(&head, 1024);
    print_listint(head);
    free_listint(head);
    head = NULL;
    return (0);
}
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ gcc -Wall -pedantic -Werror -Wextra 4-main.c 3-add_nodeint_end.c 0-print_listint.c 4-free_listint.c -o e
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ valgrind ./e 
==3643== Memcheck, a memory error detector
==3643== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==3643== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==3643== Command: ./e
==3643== 
0
1
2
3
4
98
402
1024
==3643== 
==3643== HEAP SUMMARY:
==3643==     in use at exit: 0 bytes in 0 blocks
==3643==   total heap usage: 9 allocs, 9 frees, 1,152 bytes allocated
==3643== 
==3643== All heap blocks were freed -- no leaks are possible
==3643== 
==3643== For counts of detected and suppressed errors, rerun with: -v
==3643== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$

Free

Write a function that frees a listint_t list.

  • Prototype: void free_listint2(listint_t **head);
  • The function sets the head to NULL
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ cat 5-main.c 
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "lists.h"

/**
 * main - check the code for Holberton School students.
 *
 * Return: Always 0.
 */
int main(void)
{
    listint_t *head;

    head = NULL;
    add_nodeint_end(&head, 0);
    add_nodeint_end(&head, 1);
    add_nodeint_end(&head, 2);
    add_nodeint_end(&head, 3);
    add_nodeint_end(&head, 4);
    add_nodeint_end(&head, 98);
    add_nodeint_end(&head, 402);
    add_nodeint_end(&head, 1024);
    print_listint(head);
    free_listint2(&head);
    printf("%p\n", (void *)head);
    return (0);
}
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ gcc -Wall -pedantic -Werror -Wextra 5-main.c 3-add_nodeint_end.c 0-print_listint.c 5-free_listint2.c -o f
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ valgrind ./f 
==3843== Memcheck, a memory error detector
==3843== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==3843== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==3843== Command: ./f
==3843== 
0
1
2
3
4
98
402
1024
(nil)
==3843== 
==3843== HEAP SUMMARY:
==3843==     in use at exit: 0 bytes in 0 blocks
==3843==   total heap usage: 9 allocs, 9 frees, 1,152 bytes allocated
==3843== 
==3843== All heap blocks were freed -- no leaks are possible
==3843== 
==3843== For counts of detected and suppressed errors, rerun with: -v
==3843== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$

Pop

Write a function that deletes the head node of a listint_t linked list, and returns the head node’s data (n).

  • Prototype: int pop_listint(listint_t **head);
  • if the linked list is empty return 0 Solution: 6-pop_listint.c
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ cat 6-main.c 
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "lists.h"

/**
 * main - check the code for Holberton School students.
 *
 * Return: Always 0.
 */
int main(void)
{
    listint_t *head;
    int n;

    head = NULL;
    add_nodeint_end(&head, 0);
    add_nodeint_end(&head, 1);
    add_nodeint_end(&head, 2);
    add_nodeint_end(&head, 3);
    add_nodeint_end(&head, 4);
    add_nodeint_end(&head, 98);
    add_nodeint_end(&head, 402);
    add_nodeint_end(&head, 1024);
    print_listint(head);
    n = pop_listint(&head);
    printf("- %d\n", n);
    print_listint(head);
    n = pop_listint(&head);
    printf("- %d\n", n);
    print_listint(head);
    free_listint2(&head);
    printf("%p\n", (void *)head);
    return (0);
}
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ gcc -Wall -pedantic -Werror -Wextra 6-main.c 3-add_nodeint_end.c 0-print_listint.c 5-free_listint2.c 6-pop_listint.c -o g
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ valgrind ./g 
==4369== Memcheck, a memory error detector
==4369== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==4369== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==4369== Command: ./g
==4369== 
0
1
2
3
4
98
402
1024
- 0
1
2
3
4
98
402
1024
- 1
2
3
4
98
402
1024
(nil)
==4369== 
==4369== HEAP SUMMARY:
==4369==     in use at exit: 0 bytes in 0 blocks
==4369==   total heap usage: 9 allocs, 9 frees, 1,152 bytes allocated
==4369== 
==4369== All heap blocks were freed -- no leaks are possible
==4369== 
==4369== For counts of detected and suppressed errors, rerun with: -v
==4369== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$

Get node at index

Write a function that returns the nth node of a listint_t linked list.

  • Prototype: listint_t *get_nodeint_at_index(listint_t *head, unsigned int index);
  • where index is the index of the node, starting at 0
  • if the node does not exist, return NULL

Solution: 7-get_nodeint.c

$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ cat 7-main.c 
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "lists.h"

/**
 * main - check the code for Holberton School students.
 *
 * Return: Always 0.
 */
int main(void)
{
    listint_t *head;
    listint_t *node;

    head = NULL;
    add_nodeint_end(&head, 0);
    add_nodeint_end(&head, 1);
    add_nodeint_end(&head, 2);
    add_nodeint_end(&head, 3);
    add_nodeint_end(&head, 4);
    add_nodeint_end(&head, 98);
    add_nodeint_end(&head, 402);
    add_nodeint_end(&head, 1024);
    print_listint(head);
    node = get_nodeint_at_index(head, 5);
    printf("%d\n", node->n);
    print_listint(head);
    free_listint2(&head);
    return (0);
}
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ gcc -Wall -pedantic -Werror -Wextra 7-main.c 3-add_nodeint_end.c 0-print_listint.c 5-free_listint2.c 7-get_nodeint.c -o h
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ ./h 
0
1
2
3
4
98
402
1024
98
0
1
2
3
4
98
402
1024
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$

Sum list

Write a function that returns the sum of all the data (n) of a listint_t linked list.

  • Prototype: int sum_listint(listint_t *head);
  • if the list is empty, return 0

Solution: 8-sum_listint.c

$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ cat 8-main.c 
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "lists.h"

/**
 * main - check the code for Holberton School students.
 *
 * Return: Always 0.
 */
int main(void)
{
    listint_t *head;
    int sum;

    head = NULL;
    add_nodeint_end(&head, 0);
    add_nodeint_end(&head, 1);
    add_nodeint_end(&head, 2);
    add_nodeint_end(&head, 3);
    add_nodeint_end(&head, 4);
    add_nodeint_end(&head, 98);
    add_nodeint_end(&head, 402);
    add_nodeint_end(&head, 1024);
    sum = sum_listint(head);
    printf("sum = %d\n", sum);
    free_listint2(&head);
    return (0);
}
$ amonkeyprogrammer@ubuntu:~/c0x13. More singly linked lists$ gcc -Wall -pedantic -Werror -Wextra 8-main.c 3-add_nodeint_end.c 5-free_listint2.c 8-sum_listint.c -o i
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ ./i 
sum = 1534
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$

Insert

Write a function that inserts a new node at a given position.

  • Prototype: listint_t *insert_nodeint_at_index(listint_t **head, unsigned int idx, int n);
  • where idx is the index of the list where the new node should be added. Index starts at 0
  • Returns: the address of the new node, or NULL if it failed
  • if it is not possible to add the new node at index idx, do not add the new node and return NULL

Solution: 9-insert_nodeint.c

$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ cat 9-main.c 
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "lists.h"

/**
 * main - check the code for Holberton School students.
 *
 * Return: Always 0.
 */
int main(void)
{
    listint_t *head;

    head = NULL;
    add_nodeint_end(&head, 0);
    add_nodeint_end(&head, 1);
    add_nodeint_end(&head, 2);
    add_nodeint_end(&head, 3);
    add_nodeint_end(&head, 4);
    add_nodeint_end(&head, 98);
    add_nodeint_end(&head, 402);
    add_nodeint_end(&head, 1024);
    print_listint(head);
    printf("-----------------\n");
    insert_nodeint_at_index(&head, 5, 4096);
    print_listint(head);
    free_listint2(&head);
    return (0);
}
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ gcc -Wall -pedantic -Werror -Wextra 9-main.c 3-add_nodeint_end.c 0-print_listint.c 5-free_listint2.c 9-insert_nodeint.c -o j
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ ./j 
0
1
2
3
4
98
402
1024
-----------------
0
1
2
3
4
4096
98
402
1024
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$

Delete at index

Write a function that deletes the node at index index of a listint_t linked list.

  • Prototype: int delete_nodeint_at_index(listint_t **head, unsigned int index);
  • where index is the index of the node that should be deleted. Index starts at 0
  • Returns: 1 if it succeeded, -1 if it failed

Solution: 10-delete_nodeint.c

$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ cat 10-main.c 
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "lists.h"

/**
 * main - check the code for Holberton School students.
 *
 * Return: Always 0.
 */
int main(void)
{
    listint_t *head;

    head = NULL;
    add_nodeint_end(&head, 0);
    add_nodeint_end(&head, 1);
    add_nodeint_end(&head, 2);
    add_nodeint_end(&head, 3);
    add_nodeint_end(&head, 4);
    add_nodeint_end(&head, 98);
    add_nodeint_end(&head, 402);
    add_nodeint_end(&head, 1024);
    print_listint(head);
    printf("-----------------\n");
    delete_nodeint_at_index(&head, 5);
    print_listint(head);
    printf("-----------------\n");
    delete_nodeint_at_index(&head, 0);
    print_listint(head);
    printf("-----------------\n");
    delete_nodeint_at_index(&head, 0);
    print_listint(head);
    printf("-----------------\n");
    delete_nodeint_at_index(&head, 0);
    print_listint(head);
    printf("-----------------\n");
    delete_nodeint_at_index(&head, 0);
    print_listint(head);
    printf("-----------------\n");
    delete_nodeint_at_index(&head, 0);
    print_listint(head);
    printf("-----------------\n");
    delete_nodeint_at_index(&head, 0);
    print_listint(head);
    printf("-----------------\n");
    delete_nodeint_at_index(&head, 0);
    printf("-----------------\n");
    delete_nodeint_at_index(&head, 0);
    printf("-----------------\n");
    delete_nodeint_at_index(&head, 0);
    printf("-----------------\n");
    delete_nodeint_at_index(&head, 0);
    printf("-----------------\n");
    delete_nodeint_at_index(&head, 0);
    printf("-----------------\n");
    delete_nodeint_at_index(&head, 0);
    printf("-----------------\n");
    delete_nodeint_at_index(&head, 0);
    printf("-----------------\n");
    delete_nodeint_at_index(&head, 0);
    printf("-----------------\n");
    delete_nodeint_at_index(&head, 0);
    printf("-----------------\n");
    delete_nodeint_at_index(&head, 0);
    print_listint(head);
    return (0);
}
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ gcc -Wall -pedantic -Werror -Wextra 10-main.c 3-add_nodeint_end.c 0-print_listint.c 5-free_listint2.c 10-delete_nodeint.c -o k
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ valgrind ./k 
==5571== Memcheck, a memory error detector
==5571== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==5571== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==5571== Command: ./k
==5571== 
0
1
2
3
4
98
402
1024
-----------------
0
1
2
3
4
402
1024
-----------------
1
2
3
4
402
1024
-----------------
2
3
4
402
1024
-----------------
3
4
402
1024
-----------------
4
402
1024
-----------------
402
1024
-----------------
1024
-----------------
-----------------
-----------------
-----------------
-----------------
-----------------
-----------------
-----------------
-----------------
-----------------
==5571== 
==5571== HEAP SUMMARY:
==5571==     in use at exit: 0 bytes in 0 blocks
==5571==   total heap usage: 9 allocs, 9 frees, 1,152 bytes allocated
==5571== 
==5571== All heap blocks were freed -- no leaks are possible
==5571== 
==5571== For counts of detected and suppressed errors, rerun with: -v
==5571== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$

Reverse list

Write a function that reverses a listint_t linked list.

  • Prototype: listint_t *reverse_listint(listint_t **head);
  • Returns: a pointer to the first node of the reversed list
  • You are not allowed to use more than 1 loop.
  • You are not allowed to use malloc, free or arrays
  • You can only declare a maximum of two variables in your function

Solution: 100-reverse_listint.c

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "lists.h"

/**
 * main - check the code for Holberton School students.
 *
 * Return: Always 0.
 */
int main(void)
{
    listint_t *head;

    head = NULL;
    add_nodeint_end(&head, 0);
    add_nodeint_end(&head, 1);
    add_nodeint_end(&head, 2);
    add_nodeint_end(&head, 3);
    add_nodeint_end(&head, 4);
    add_nodeint_end(&head, 98);
    add_nodeint_end(&head, 402);
    add_nodeint_end(&head, 1024);
    print_listint(head);
    reverse_listint(&head);
    print_listint(head);    
    free_listint2(&head);
    return (0);
}
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ gcc -Wall -pedantic -Werror -Wextra 100-main.c 3-add_nodeint_end.c 0-print_listint.c 5-free_listint2.c 100-reverse_listint.c -o l
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$ valgrind ./l 
==3117== Memcheck, a memory error detector
==3117== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==3117== Using Valgrind-3.11.0 and LibVEX; rerun with -h for copyright info
==3117== Command: ./l
==3117== 
0
1
2
3
4
98
402
1024
1024
402
98
4
3
2
1
0
==3117== 
==3117== HEAP SUMMARY:
==3117==     in use at exit: 0 bytes in 0 blocks
==3117==   total heap usage: 9 allocs, 9 frees, 1,152 bytes allocated
==3117== 
==3117== All heap blocks were freed -- no leaks are possible
==3117== 
==3117== For counts of detected and suppressed errors, rerun with: -v
==3117== ERROR SUMMARY: 0 errors from 0 contexts (suppressed: 0 from 0)
$ amonkeyprogrammer@ubuntu:~/0x13. More singly linked lists$

Print (safe version)

Write a function that prints a listint_t linked list.

  • Prototype: size_t print_listint_safe(const listint_t *head);
  • Returns: the number of nodes in the list
  • This function can print lists with a loop
  • You should go through the list only once
  • If the function fails, exit the program with status 98
  • Output format: see example

Solution 101-print_listint_safe.c

julien@ubuntu:~/0x13. More singly linked lists$ cat 101-main.c 
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "lists.h"

/**
 * main - check the code
 *
 * Return: Always 0.
 */
int main(void)
{
    listint_t *head;
    listint_t *head2;
    listint_t *node;

    head2 = NULL;
    add_nodeint(&head2, 0);
    add_nodeint(&head2, 1);
    add_nodeint(&head2, 2);
    add_nodeint(&head2, 3);
    add_nodeint(&head2, 4);
    add_nodeint(&head2, 98);
    add_nodeint(&head2, 402);
    add_nodeint(&head2, 1024);
    print_listint_safe(head2);
    head = NULL;
    node = add_nodeint(&head, 0);
    add_nodeint(&head, 1);
    add_nodeint(&head, 2);
    add_nodeint(&head, 3);
    add_nodeint(&head, 4);
    node->next = add_nodeint(&head, 98);
    add_nodeint(&head, 402);
    add_nodeint(&head, 1024);
    print_listint_safe(head);
    return (0);
}
julien@ubuntu:~/0x13. More singly linked lists$ gcc -Wall -pedantic -Werror -Wextra -std=gnu89 101-main.c 2-add_nodeint.c 101-print_listint_safe.c -o m
julien@ubuntu:~/0x13. More singly linked lists$ ./m
[0x1b500f0] 1024
[0x1b500d0] 402
[0x1b500b0] 98
[0x1b50090] 4
[0x1b50070] 3
[0x1b50050] 2
[0x1b50030] 1
[0x1b50010] 0
[0x1b50600] 1024
[0x1b505e0] 402
[0x1b505c0] 98
[0x1b505a0] 4
[0x1b50580] 3
[0x1b50560] 2
[0x1b50540] 1
[0x1b50110] 0
-> [0x1b505c0] 98
julien@ubuntu:~/0x13. More singly linked lists$

Free (safe version)

Write a function that frees a listint_t list.

  • Prototype: size_t free_listint_safe(listint_t **h);
  • This function can free lists with a loop
  • You should go though the list only once
  • Returns: the size of the list that was free’d
  • The function sets the head to NULL

Solution: 102-free_listint_safe.c

julien@ubuntu:~/0x13. More singly linked lists$ cat 102-main.c 
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "lists.h"

/**
 * main - check the code
 *
 * Return: Always 0.
 */
int main(void)
{
    listint_t *head;
    listint_t *head2;
    listint_t *node;

    head2 = NULL;
    add_nodeint(&head2, 0);
    add_nodeint(&head2, 1);
    add_nodeint(&head2, 2);
    add_nodeint(&head2, 3);
    add_nodeint(&head2, 4);
    add_nodeint(&head2, 98);
    add_nodeint(&head2, 402);
    add_nodeint(&head2, 1024);
    print_listint_safe(head2);
    head = NULL;
    node = add_nodeint(&head, 0);
    add_nodeint(&head, 1);
    add_nodeint(&head, 2);
    add_nodeint(&head, 3);
    add_nodeint(&head, 4);
    node->next = add_nodeint(&head, 98);
    add_nodeint(&head, 402);
    add_nodeint(&head, 1024);
    print_listint_safe(head);
    free_listint_safe(&head2);
    free_listint_safe(&head);
    printf("%p, %p\n", (void *)head2, (void *)head);
    return (0);
}
julien@ubuntu:~/0x13. More singly linked lists$ gcc -Wall -pedantic -Werror -Wextra -std=gnu89 102-main.c 2-add_nodeint.c 101-print_listint_safe.c 102-free_listint_safe.c -o n
julien@ubuntu:~/0x13. More singly linked lists$ ./n 
[0x11260f0] 1024
[0x11260d0] 402
[0x11260b0] 98
[0x1126090] 4
[0x1126070] 3
[0x1126050] 2
[0x1126030] 1
[0x1126010] 0
[0x1126600] 1024
[0x11265e0] 402
[0x11265c0] 98
[0x11265a0] 4
[0x1126580] 3
[0x1126560] 2
[0x1126540] 1
[0x1126110] 0
-> [0x11265c0] 98
(nil), (nil)
julien@ubuntu:~/0x13. More singly linked lists$ 

Find the loop

Write a function that finds the loop in a linked list.

  • Prototype: listint_t *find_listint_loop(listint_t *head);
  • Returns: The address of the node where the loop starts, or NULL if there is no loop
  • You are not allowed to use malloc, free or arrays
  • You can only declare a maximum of two variables in your function

Solution: 103-find_loop.c

julien@ubuntu:~/0x13. More singly linked lists$ cat 103-main.c 
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include "lists.h"

/**
 * main - check the code
 *
 * Return: Always 0.
 */
int main(void)
{
    listint_t *head;
    listint_t *head2;
    listint_t *node;

    head2 = NULL;
    add_nodeint(&head2, 0);
    add_nodeint(&head2, 1);
    add_nodeint(&head2, 2);
    add_nodeint(&head2, 3);
    add_nodeint(&head2, 4);
    add_nodeint(&head2, 98);
    add_nodeint(&head2, 402);
    add_nodeint(&head2, 1024);
    print_listint_safe(head2);
    node = find_listint_loop(head2);
    if (node != NULL)
    {
        printf("Loop starts at [%p] %d\n", (void *)node, node->n);
    }
    free_listint_safe(&head2);
    head = NULL;
    node = add_nodeint(&head, 0);
    add_nodeint(&head, 1);
    add_nodeint(&head, 2);
    add_nodeint(&head, 3);
    add_nodeint(&head, 4);
    add_nodeint(&head, 5);
    add_nodeint(&head, 6);
    node->next = add_nodeint(&head, 7);
    add_nodeint(&head, 98);
    add_nodeint(&head, 402);
    add_nodeint(&head, 1024);
    print_listint_safe(head);
    node = find_listint_loop(head);
    if (node != NULL)
    {
        printf("Loop starts at [%p] %d\n", (void *)node, node->n);
    }
    free_listint_safe(&head);
    return (0);
}
julien@ubuntu:~/0x13. More singly linked lists$ gcc -Wall -pedantic -Werror -Wextra -std=gnu89 103-main.c 2-add_nodeint.c 101-print_listint_safe.c 102-free_listint_safe.c 103-find_loop.c -o o
julien@ubuntu:~/0x13. More singly linked lists$ ./o 
[0x13700f0] 1024
[0x13700d0] 402
[0x13700b0] 98
[0x1370090] 4
[0x1370070] 3
[0x1370050] 2
[0x1370030] 1
[0x1370010] 0
[0x1370560] 1024
[0x1370540] 402
[0x1370010] 98
[0x1370030] 7
[0x1370050] 6
[0x1370070] 5
[0x1370090] 4
[0x13700b0] 3
[0x13700d0] 2
[0x13700f0] 1
[0x1370110] 0
-> [0x1370030] 7
Loop starts at [0x1370030] 7
julien@ubuntu:~/0x13. More singly linked lists$