c链表（创建、显示、释放）
未隐藏细节的链表如下：
#define _CRT_SECURE_NO_WARNINGS
/* binary.c -- prints integer in binary form */
/* films2.c -- using a linked list of structures */
#include /* has the malloc prototype */
#include /* 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 */
};
int main(void)
{
struct film * head = NULL;
struct film * prev=NULL, *current=NULL;
char input[TSIZE];
/* Gather and store information */
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", ¤t->rating);
while (getchar() != '\n')
continue;
puts("Enter next movie title (empty line to stop):");
prev = current;
}
/* Show list of movies */
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;
}
/* Program done, so free allocated memory */
current = head;
while (current != NULL)//这里注意释放顺序
{
struct film * tmp;
tmp = current->next;
free(current);
current = tmp;
}
printf("Bye!\n");
printf("\n");
system("pause");
return 0;
}
隐藏细节，只留下接口的链表程序如下：
头文件如下：
/* list.h -- header file for a simple list type */
#ifndef LIST_H_
#define LIST_H_
#include /* C99 feature */
/* program-specific declarations */
#define TSIZE 45 /* size of array to hold title */
struct film
{
char title[TSIZE];
int rating;
};
/* general type definitions */
typedef struct film Item;
typedef struct node
{
Item item;
struct node * next;
} Node;
typedef Node * List;
/* function prototypes */
/* operation: initialize a list */
/* preconditions: plist points to a list */
/* postconditions: the list is initialized to empty */
void InitializeList(List * plist);
/* operation: determine if list is empty */
/* plist points to an initialized list */
/* postconditions: function returns True if list is empty */
/* and returns False otherwise */
bool ListIsEmpty(const List *plist);
/* operation: determine if list is full */
/* plist points to an initialized list */
/* postconditions: function returns True if list is full */
/* and returns False otherwise */
bool ListIsFull(const List *plist);
/* operation: determine number of items in list */
/* plist points to an initialized list */
/* postconditions: function returns number of items in list */
unsigned int ListItemCount(const List *plist);
/* operation: add item to end of list */
/* preconditions: item is an item to be added to list */
/* plist points to an initialized list */
/* postconditions: if possible, function adds item to end */
/* of list and returns True; otherwise the */
/* function returns False */
bool AddItem(Item item, List * plist);
/* operation: apply a function to each item in list */
/* plist points to an initialized list */
/* pfun points to a function that takes an */
/* Item argument and has no return value */
/* postcondition: the function pointed to by pfun is */
/* executed once for each item in the list */
void Traverse (const List *plist, void (* pfun)(Item item) );
/* operation: free allocated memory, if any */
/* plist points to an initialized list */
/* postconditions: any memory allocated for the list is freed */
/* and the list is set to empty */
void EmptyTheList(List * plist);
#endif链表操作函数实现如下：
/* list.c -- functions supporting list operations */
#include main函数如下：
/* films3.c -- using an ADT-style linked list */
/* compile with list.c */
//#define _CRT_SECURE_NO_WARNINGS
#include /* prototype for exit() */
#include "list.h" /* defines List, Item */
void showmovies(Item item);
int main(void)
{
List movies;
Item temp;
/* initialize */
InitializeList(&movies);
if (ListIsFull(&movies))
{
fprintf(stderr, "No memory available! Bye!\n");
exit(1);
}
/* gather and store */
puts("Enter first movie title:");
while (gets_s(temp.title,20) != NULL && temp.title[0] != '\0')
{
puts("Enter your rating <0-10>:");
scanf_s("%d", &temp.rating,10);
while (getchar() != '\n')
continue;
if (AddItem(temp, &movies) == false)
{
fprintf(stderr, "Problem allocating memory\n");
break;
}
if (ListIsFull(&movies))
{
puts("The list is now full.");
break;
}
puts("Enter next movie title (empty line to stop):");
}
/* display */
if (ListIsEmpty(&movies))
printf("No data entered. ");
else
{
printf("Here is the movie list:\n");
Traverse(&movies, showmovies);
}
printf("You entered %d movies.\n", ListItemCount(&movies));
/* clean up */
EmptyTheList(&movies);
printf("Bye!\n");
system("pause");
return 0;
}
void showmovies(Item item)
{
printf("Movie: %s Rating: %d\n", item.title,
item.rating);
}