Provide some more fun program examples

[Wavesonics]

That swap example is a good one, how about others? At least having them on a wiki on the github here would be nice.

[Wavesonics]

pointer_increment.txt

void demo()
{
    char a[] = "hi";
    char * p = a;
    ++p;
    ++p;
    ++p;
}

[Wavesonics]

swap_bugged.txt

void swap(const char ** p, const char ** q)
{
    const char * t;
    t = *p;
    *p = *q;
    *q = t;
}

int main()
{
    const char * a = "hey";
    const char * b = "you";
    
    printf("%s %s\n", a, b);
    swap(&a, &b);
    printf("%s %s\n", a, b);
}

[Wavesonics]

swap_correct.txt

void swap(const char ** p, const char ** q)
{
    const char * t;
    t = *p;
    *p = *q;
    *q = t;
}

int main()
{
    const char * a = "hey";
    const char * b = "you";
    
    printf("%s %s\n", a, b);
    swap(&a, &b);
    printf("%s %s\n", a, b);
}

[Wavesonics]

linkedlist.txt

struct linkedlist {
    struct linkedlist *next;
    int data;
};

struct linkedlist null;

void addToList(struct linkedlist **l, int data)
{
    struct linkedlist *temp = malloc(sizeof(struct linkedlist));
    temp->next = *l;
    temp->data = data;
    *l = temp;
}

void printList(struct linkedlist *l)
{
    if (l == &null) return;
    printList(l->next);
    printf("%d\n", l->data);
}

void deleteList(struct linkedlist *l)
{
    if (l == &null) return;
    deleteList(l->next);
    free(l);
}

int main()
{
    struct linkedlist *myList = &null;
    
    addToList(&myList, 10);
    addToList(&myList, 12);
    addToList(&myList, 16);
    printList(myList);
    deleteList(myList);
    
    return 0;
}