C 语言中的链表语法

Question

我试图通过图表可视化来理解链表的语法。然而，我感到困惑。此代码打印出 0-9。我不明白评论的位，请直观地解释一下。

#include <stdio.h>
#include <stdlib.h>
struct node
{
    int item;
    struct node* link;
};
int main()
{
    struct node *start,*list;
    int i;
    start = (struct node *)malloc(sizeof(struct node)); //???????
    list = start; // ????????
    start->link = NULL; // ??????????
    for(i=0;i<10;i++)
    {
        list->item = i;
        list->link = (struct node *)malloc(sizeof(struct node));
        list = list->link;
    }
    list->link = NULL; //????????????
    while(start != NULL) //??????????????
    {
        printf("%dn",start->item);
        start = start->link;
    }
    return 0;
} 

Answer 1

int main()
{
    struct node *start,*list;
    int i;
    // Allocate memory for a single node
    start = (struct node *)malloc(sizeof(struct node)); //???????
    // The head of the list is starting node.
    // (This head represented by `list` will be advanced when building;
    //  while the head represented by `start` will not be advanced
    //  until iterating for display.)
    list = start; // ????????
    // The starting node has no 'next' yet.
    // (This is not technically needed in this exact code.
    //  The code would have been more clear with the assignment of
    //  null to the 'next' after each malloc to start with a clean node.)
    start->link = NULL; // ??????????
    for(i = 0; i < 10; i++)
    {
        list->item = i;
        list->link = (struct node *)malloc(sizeof(struct node));
        list = list->link; // Move to the next (newly created) node.
    }
    // The last node has no 'next' node. Need to manually assign it
    // a value because it "could be anything" until properly initialized.
    // (Intermediate nodes have had the 'next' assigned in the loop.)
    list->link = NULL; //????????????
    // Iterate over the list, using `start` to track the head and
    // keep iterating until the end of the list is reached.
    while(start != NULL) //??????????????
    {
        printf("%dn",start->item);
        start = start->link; // Move to the 'next' node
    }
    return 0;
}

将其与以下内容进行比较，希望可以使目标/意图更加明确：

struct node *create_node(int value) {
    struct node *n = malloc(sizeof(struct node));
    n->item = value; // all nodes start with some value
    n->link = NULL;  // all nodes start without a 'next'
    return n;
}
int main()
{
    struct node *start,*list;
    int i;
    // Create list of elements 0..9
    // (Creating the start node first avoids a condition check;
    //  pulling out the value assignment from the subsequent/trailing loop
    //  is for clarity.)
    start = create_node(0);
    list = start;
    for(i = 1; i < 10; i++) // Changed loop count - value assigned in create
    {
        list->link = create_node(i);
        list = list->link;
    }
    // Display - note reset of tracked head to beginning of list
    list = start;
    while(list != NULL)
    {
        printf("%dn", list->item);
        list = list->link;
    }
    return 0;
}