巨人公司的机群由12个座位的飞机组成。它每天飞行一个航班。根据下面的要求，编写一个座位预订程序。

/巨人公司的机群由12个座位的飞机组成。它每天飞行一个航班。根据下面的要求，编写一个座位预订程序。
a.该程序使用一个含12个结构体组成的数组。每个结构体中包括：一个成员表示座位编号，一个成员表示座位号是否已经被预订，一个成员表示预订人的名，一个成员表示预订人的姓。
b.该程序显示下面的菜单：
To choose a function,enter its letter label:
a) Show number of empty seats
b) Show list of empty seats
c) Show alphabetical list of seats
d) Assign a cutomer to a seat assignment
e) Delete a seat assignment
f) Quit
c.该程序能成功执行上面给出的菜单。选择d)和e)要提示用户进行额外输入，每个选项都能让用户中止输入
d.执行特定程序后，该程序再次显示菜单，除非用户选择f)。/

#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#define SEAT_NUM 12

typedef struct
{
    int seat_number;     
    int is_booked;       
    char first_name[30]; 
    char last_name[30];
} Seat;
void show_empty_seat_count(Seat seats[])
{
    int count = 0;
    for (int i = 0; i < SEAT_NUM; i++)
    {
        if (!seats[i].is_booked)
        {
            count++;
        }
    }
    printf("空座位数量: %d\n", count);
}
void show_empty_seats(Seat seats[])
{
    printf("空座位编号: ");
    for (int i = 0; i < SEAT_NUM; i++)
    {
        if (!seats[i].is_booked)
        {
            printf("%d ", seats[i].seat_number);
        }
    }
    printf("\n");
}
void show_alphabetical_seats(Seat seats[])
{
    Seat booked_seats[SEAT_NUM];
    int count = 0;
    for (int i = 0; i < SEAT_NUM; i++)
    {
        if (seats[i].is_booked)
        {
            booked_seats[count++] = seats[i];
        }
    }
    for (int i = 0; i < count - 1; i++)
    {
        for (int j = i + 1; j < count; j++)
        {
            if (strcmp(booked_seats[i].last_name, booked_seats[j].last_name) > 0)
            {
                Seat temp = booked_seats[i];
                booked_seats[i] = booked_seats[j];
                booked_seats[j] = temp;
            }
        }
    }
    printf("已预订座位（按姓氏排序）:\n");
    for (int i = 0; i < count; i++)
    {
        printf("座位编号: %d, 预订人: %s %s\n",
        booked_seats[i].seat_number,
        booked_seats[i].first_name,
        booked_seats[i].last_name);
    }
}

void assign_customer_to_seat(Seat seats[])
{
    int seat_number;
    printf("请输入座位编号(1-%d): ", SEAT_NUM);
    scanf("%d", &seat_number);
    seat_number--;
    if (seat_number < 0 || seat_number >= SEAT_NUM)
    {
        printf("座位编号无效！\n");
        return;
    }
    if (seats[seat_number].is_booked)
    {
        printf("该座位已被预订！\n");
        return;
    }
    printf("请输入预订人名: ");
    scanf("%s", seats[seat_number].first_name);
    printf("请输入预订人姓: ");
    scanf("%s", seats[seat_number].last_name);
    seats[seat_number].is_booked = 1;
    printf("座位 %d 已成功预订。\n", seats[seat_number].seat_number);
}

void delete_seat_assignment(Seat seats[])
{
    int seat_number;
    printf("请输入要取消预订的座位编号(1-%d): ", SEAT_NUM);
    scanf("%d", &seat_number);
    seat_number--;
    if (seat_number < 0 || seat_number >= SEAT_NUM)
    {
        printf("座位编号无效！\n");
        return;
    }
    if (!seats[seat_number].is_booked)
    {
        printf("该座位尚未被预订！\n");
        return;
    }
    seats[seat_number].is_booked = 0;
    memset(seats[seat_number].first_name, 0, sizeof(seats[seat_number].first_name));
    memset(seats[seat_number].last_name, 0, sizeof(seats[seat_number].last_name));
    printf("座位 %d 的预订已成功取消。\n", seats[seat_number].seat_number);
}

int main(void)
{
    Seat seats[SEAT_NUM];
    for (int i = 0; i < SEAT_NUM; i++)
    {
        seats[i].seat_number = i + 1;
        seats[i].is_booked = 0;
    }
    char choice;
    do
    {
        printf("\nTo choose a function,enter its letter label:\n");
        printf("a) Show number of empty seats\n");
        printf("b) Show list of empty seats\n");
        printf("c) Show alphabetical list of seats\n");
        printf("d) Assign a cutomer to a seat assignment\n");
        printf("e) Delete a seat assignment\n");
        printf("f) Quit\n");
        printf("选择: ");
        choice = getchar();
        getchar();        //清除缓冲区，getchar()函数每次读取一个字符，换行符也是字符
        switch (choice)
        {
            case 'a':  
                show_empty_seat_count(seats);  
                break;  
            case 'b':  
                show_empty_seats(seats);  
                break;  
            case 'c':  
                show_alphabetical_seats(seats);  
                break;  
            case 'd':  
                assign_customer_to_seat(seats);  
                break;  
            case 'e':  
                delete_seat_assignment(seats);  
                break;  
            case 'f':
                printf("退出程序。\n");
                //exit(0);
                break;
            default:
                printf("无效选择，请重试。\n");
                break;
        }
    }while(choice!='f');
    return 0;
}