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

// STEP 0:  Original syntax
//
// Problem:  (*curr).value is ugly.
// Solution:  curr -> value
//
// Problem:  while loop is more error-prone than a for loop (and violates code quality
//           standard for the course).
// Solution: Use a for loop to iterate over a linked list.
//
// Problem:  Making the struct objects on the stack (in function with name) is limiting.
// Solution: Use malloc(…)
//
// Problem:  Typing `struct Node` is more cumbersome than typing `Node`.
// Solution: Don't be lazy.
//
// Problem²: I am lazy.
// Solution: Use typedef.

typedef struct _Node {
    int value;
    struct _Node* next;
} Node;

void print_list(Node* head) {  // print_list(…) now takes address of the head node
    for(Node* curr = head;  curr != NULL;  curr = curr -> next) {
        printf("[%d]", curr -> value);
        
        // If this is not the tail, then print a '─' to connect to the next node.
        if(curr -> next != NULL) {
            printf("─");
        }
    }
    printf("\n");
}

void _append(int value, Node** a_head, Node** a_tail) {
    Node* new_node = malloc(sizeof(*new_node)); // allocate space for one new node
    new_node -> value = value;  // set its .value field

    if(*a_head == NULL) {  // list was empty
        *a_head = new_node;
        *a_tail = new_node;
        // We now have a list of size 1.
    }
    else {
        (*a_tail) -> next = new_node;
        new_node -> next = NULL;
        *a_tail = new_node;  // Don't forget!!!  Every time we add a node to the end,
                             // the tail changes.
        // We now have a list of size ≥2
    }
}

int main(int argc, char* argv[]) {
    Node* head = NULL;  // linked list of size 0.
    Node* tail = head;
    _append(5, &head, &tail);
    print_list(head);

    _append(6, &head, &tail);
    print_list(head);

    _append(7, &head, &tail);
    print_list(head);


    print_list(head);
    
    return EXIT_SUCCESS;
}
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