一个正序跟逆序输出的列表的C程序，求解释其中的一个函数

一个正序和逆序输出的列表的C程序，求解释其中的一个函数
#include <stdio.h>
#include <stdlib.h> /* has the malloc prototype */
#include <string.h> /* has the strcpy prototype */
#define TSIZE 45 /* size of array to hold title */
struct film {
  char title[TSIZE];
  int rating;
  struct film * next; /* points to next struct in list */
};

void show_rec(const struct film * pf); /* recursive function */
int main(void)
{
  struct film * head = NULL;
  struct film * prev, * current;
  char input[TSIZE];

  puts("Enter first movie title:");
  while (gets(input) != NULL && input[0] != '\0')
  {
  current = (struct film *) malloc(sizeof(struct film));
  if (head == NULL) /* first structure */
  head = current;
  else /* subsequent structures */
  prev->next = current;
  current->next = NULL;
  strcpy(current->title, input);
  puts("Enter your rating <0-10>:");
  scanf("%d", &current->rating);
  while(getchar() != '\n')
  continue;
  puts("Enter next movie title (empty line to stop):");
  prev = current;
  }
  if (head == NULL)
  printf("No data entered. ");
  else
  printf ("Here is the movie list:\n");
  current = head;
  while (current != NULL)
  {
  printf("Movie: %s Rating: %d\n", current->title, current->rating);
  current = current->next;
  }
  if (head != NULL)
  {
  printf("\nHere is the list in reverse order:\n");
  show_rec(head);
  }
  printf("Bye!\n");
  return 0;
}

void show_rec(const struct film * pf)/* 工作原理是什么？为什么能这样？我认为只会连续输出最后一项 */

{
  if (pf->next != NULL)
  show_rec(pf->next);
  printf("Movie: %s Rating: %d\n", pf->title, pf->rating);
}


------解决方案--------------------
递归嘛 没什么好讲的 谷歌递归函数
------解决方案--------------------
用递归来实现从最后一个节点开始输出啊