seer/tests/hellolinklist/hellolinklist.cpp

#include <string>
#include <iostream>
#include <string.h>
#include <malloc.h>
#include <stdio.h>
#include <stdlib.h>

// https://www.geeksforgeeks.org/linked-list-set-1-introduction/
//
// C program to implement a linked list
//

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

// Driver's code
int main() {

    struct Node* head   = NULL;
    struct Node* second = NULL;
    struct Node* third  = NULL;

    // allocate 3 nodes in the heap
    head   = (struct Node*)malloc(sizeof(struct Node));
    second = (struct Node*)malloc(sizeof(struct Node));
    third  = (struct Node*)malloc(sizeof(struct Node));

    /* Three blocks have been allocated dynamically.
       We have pointers to these three blocks as head,
       second and third
         head           second           third
          |                |               |
          |                |               |
      +---+-----+     +----+----+     +----+----+
      | #  | #  |     | #  | #  |     |  # |  # |
      +---+-----+     +----+----+     +----+----+

     # represents any random value.
     Data is random because we haven’t assigned
     anything yet
     */

    head->data = 1;      // assign data in first node
    head->next = second; // Link first node with

    // the second node

    /* data has been assigned to the data part of the first
       block (block pointed by the head). And next
       pointer of first block points to second.
       So they both are linked.

         head          second         third
          |              |              |
          |              |              |
      +---+---+     +----+----+     +-----+----+
      | 1  | o----->| #  | #  |     |  #  | #  |
      +---+---+     +----+----+     +-----+----+
    */

    // assign data to second node
    second->data = 2;

    // Link second node with the third node
    second->next = third;

    /* data has been assigned to the data part of the second
       block (block pointed by second). And next
       pointer of the second block points to the third
       block. So all three blocks are linked.

         head         second         third
          |             |             |
          |             |             |
      +---+---+     +---+---+     +----+----+
      | 1  | o----->| 2 | o-----> |  # |  # |
      +---+---+     +---+---+     +----+----+
     */

    third->data = 3; // assign data to third node
    third->next = NULL;

    /* data has been assigned to data part of third
       block (block pointed by third). And next pointer
       of the third block is made NULL to indicate
       that the linked list is terminated here.

       We have the linked list ready.

           head
             |
             |
         +---+---+     +---+---+       +----+------+
         | 1  | o----->|  2  | o-----> |  3 | NULL |
         +---+---+     +---+---+       +----+------+


       Note that only head is sufficient to represent
       the whole list.  We can traverse the complete
       list by following next pointers.
     */

    return 0;
}