用C语言设计一个航班管理系统，实现增删改查和排序的功能

好的，下面是一个基于结构体和指针的航班管理系统，它实现了增删改查和排序的功能。请注意，这只是一个示例，实际上需要更多的功能和完善的错误处理。

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#define MAX_FLIGHTS 100

typedef struct {
    char flight_number[10];
    char origin[50];
    char destination[50];
    int departure_time;
} Flight;

Flight *flights[MAX_FLIGHTS];
int num_flights = 0;

void add_flight() {
    if (num_flights >= MAX_FLIGHTS) {
        printf("Too many flights in the system.\n");
        return;
    }

    Flight *new_flight = (Flight *) malloc(sizeof(Flight));
    if (new_flight == NULL) {
        printf("Memory allocation failed.\n");
        return;
    }

    printf("Enter flight number: ");
    scanf("%s", new_flight->flight_number);
    printf("Enter origin: ");
    scanf("%s", new_flight->origin);
    printf("Enter destination: ");
    scanf("%s", new_flight->destination);
    printf("Enter departure time: ");
    scanf("%d", &new_flight->departure_time);

    flights[num_flights++] = new_flight;
    printf("Flight added successfully.\n");
}

void delete_flight() {
    char flight_number[10];
    int i, found = 0;

    printf("Enter flight number to delete: ");
    scanf("%s", flight_number);

    for (i = 0; i < num_flights; i++) {
        if (strcmp(flights[i]->flight_number, flight_number) == 0) {
            found = 1;
            break;
        }
    }

    if (found) {
        free(flights[i]);
        for (; i < num_flights - 1; i++) {
            flights[i] = flights[i + 1];
        }
        num_flights--;
        printf("Flight deleted successfully.\n");
    } else {
        printf("Flight not found.\n");
    }
}

void update_flight() {
    char flight_number[10];
    int i, found = 0;

    printf("Enter flight number to update: ");
    scanf("%s", flight_number);

    for (i = 0; i < num_flights; i++) {
        if (strcmp(flights[i]->flight_number, flight_number) == 0) {
            found = 1;
            break;
        }
    }

    if (found) {
        printf("Enter new origin: ");
        scanf("%s", flights[i]->origin);
        printf("Enter new destination: ");
        scanf("%s", flights[i]->destination);
        printf("Enter new departure time: ");
        scanf("%d", &flights[i]->departure_time);
        printf("Flight updated successfully.\n");
    } else {
        printf("Flight not found.\n");
    }
}

void search_flight() {
    char flight_number[10];
    int i, found = 0;

    printf("Enter flight number to search: ");
    scanf("%s", flight_number);

    for (i = 0; i < num_flights; i++) {
        if (strcmp(flights[i]->flight_number, flight_number) == 0) {
            found = 1;
            printf("Flight %s from %s to %s departs at %d.\n",
                flights[i]->flight_number, flights[i]->origin,
                flights[i]->destination, flights[i]->departure_time);
            break;
        }
    }

    if (!found) {
        printf("Flight not found.\n");
    }
}

int compare_flights(const void *a, const void *b) {
    Flight **flight_a = (Flight **) a;
    Flight **flight_b = (Flight **) b;
    return strcmp((*flight_a)->flight_number, (*flight_b)->flight_number);
}

void sort_flights() {
    qsort(flights, num_flights, sizeof(Flight *), compare_flights);
    printf("Flights sorted successfully.\n");
}

int main() {
    int choice;

    while (1) {
        printf("\n1. Add flight\n");
        printf("2. Delete flight\n");
        printf("3. Update flight\n");
        printf("4. Search flight\n");
        printf("5. Sort flights\n");
        printf("6. Quit\n");
        printf("Enter choice: ");
        scanf("%d", &choice);

        switch (choice) {
            case 1:
                add_flight();
                break;
            case 2:
                delete_flight();
                break;
            case 3:
                update_flight();
                break;
            case 4:
                search_flight();
                break;
            case 5:
                sort_flights();
                break;
            case 6:
                return 0;
            default:
                printf("Invalid choice.\n");
        }
    }

    return 0;
}

这个代码和前面的示例很类似，但是有一些重要的改变。为了支持动态添加和删除航班，我们使用了指向 `Flight` 结构体的指针数组 `flights`，而不是以前的静态数组。当用户添加新的航班时，我们动态地分配一个新的 `Flight` 结构体，并将其地址存储在 `flights` 数组中。当用户删除航班时，我们释放相应的内存，并将后面的指针向前移动一位。

`update_flight()` 函数实现了更新航班的功能。它让用户输入要更新的航班号，并查找该航班是否存在。如果存在，它允许用户更新航班的起始地点、目的地和出发时间。

`compare_flights()` 函数是用来比较两个航班的航班号的辅助函数。它将两个 `Flight` 指针强制转换为 `Flight **`，并使用 `strcmp()` 函数比较航班号。

`sort_flights()` 函数实现了对航班按照航班号排序的功能。它使用 `qsort()` 函数，将 `flights` 数组中的航班指针按照航班号进行排序。

这个程序的控制流程和前面的示例类似，但是增加了更新和排序航班的选项。