Question

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

/* Link list node */
struct node
{
    int data;
    struct node *next;
};

/* Function to reverse the linked list */
static void reverse(struct node** head_ref)
{
    struct node *prev   = NULL;
    struct node *current = *head_ref;
    struct node *next;
    while (current != NULL)
    {
        next  = current->next; 
        current->next = prev;  
        prev = current;
        current = next;
    }
    *head_ref = prev;
}

1. What are the lines that start with struct in the reverse function responsible of?
   do they extend the original struct or creating new structs that the original struct pointing to? I don’t really understand why there is no name to the original struct
2. Is there a diffrence between struct node *next; and struct node* next; ?

Answer 1

1. Line struct node *prev is declaration of variable prev of type “pointer to struct node”. These lines just declare some local variables. prev contains a pointer to the last processed node, current contains a pointer to the currently processing node and next is used to save a pointer to the next node of original list.

2. There’s no difference between struct node *next and struct node* next.