C语言链表实例

/* list.h -- header file for a simple list type */
#ifndef LIST_H_
#define LIST_H_
#include <stdbool.h>     /* 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

/* films3.c -- using an ADT-style linked list */
/* compile with list.c                        */
#include <stdio.h>
#include <stdlib.h>    /* prototype for exit() */
#include "list.h"      /* defines List, Item   */
void showmovies(Item item);
char * s_gets(char * st, int n);
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 (s_gets(temp.title, TSIZE) != NULL && temp.title[0] != '\0')
    {
        puts("Enter your rating <0-10>:");
        scanf("%d", &temp.rating);
        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");

    return 0;
}

void showmovies(Item item)
{
    printf("Movie: %s  Rating: %d\n", item.title,
           item.rating);
}

char * s_gets(char * st, int n)
{
    char * ret_val;
    char * find;

    ret_val = fgets(st, n, stdin);
    if (ret_val)
    {
        find = strchr(st, '\n');   // look for newline
        if (find)                  // if the address is not NULL,
            *find = '\0';          // place a null character there
        else
            while (getchar() != '\n')
                continue;          // dispose of rest of line
    }
    return ret_val;
}