数据结构车票管理系统的实验课设，用C语言来实现，要有完整源代码

以下是一个简单的车票管理系统的实验课设，使用 C 语言编写，包括完整的源代码：

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

#define FILENAME "tickets.txt" // 存储车票信息的文件名

// 车票结构体
typedef struct {
    char train_num[10];     // 车次
    char start_city[20];    // 起点城市
    char end_city[20];      // 终点城市
    char start_time[10];    // 出发时间
    float price;            // 票价
    int remain_num;         // 剩余数量
} Ticket;

// 添加车票信息
void add_ticket(Ticket *tickets, int *num_tickets) {
    // 打开文件
    FILE *fp = fopen(FILENAME, "a");
    if (fp == NULL) {
        printf("Open file failed!\n");
        return;
    }

    // 输入车票信息
    printf("Enter train number: ");
    scanf("%s", tickets[*num_tickets].train_num);
    printf("Enter start city: ");
    scanf("%s", tickets[*num_tickets].start_city);
    printf("Enter end city: ");
    scanf("%s", tickets[*num_tickets].end_city);
    printf("Enter start time: ");
    scanf("%s", tickets[*num_tickets].start_time);
    printf("Enter price: ");
    scanf("%f", &tickets[*num_tickets].price);
    printf("Enter remain number: ");
    scanf("%d", &tickets[*num_tickets].remain_num);

    // 写入文件
    fprintf(fp, "%s %s %s %s %.2f %d\n", tickets[*num_tickets].train_num,
                                          tickets[*num_tickets].start_city,
                                          tickets[*num_tickets].end_city,
                                          tickets[*num_tickets].start_time,
                                          tickets[*num_tickets].price,
                                          tickets[*num_tickets].remain_num);

    // 关闭文件
    fclose(fp);

    // 更新票数
    (*num_tickets)++;
}

// 删除车票信息
void delete_ticket(Ticket *tickets, int *num_tickets) {
    // 打开文件
    FILE *fp = fopen(FILENAME, "r");
    if (fp == NULL) {
        printf("Open file failed!\n");
        return;
    }

    // 输入车次
    char train_num[10];
    printf("Enter train number: ");
    scanf("%s", train_num);

    // 读取文件
    Ticket temp;
    int i = 0, deleted = 0;
    while (fscanf(fp, "%s %s %s %s %f %d", temp.train_num, temp.start_city, 
                                          temp.end_city, temp.start_time, 
                                          &temp.price, &temp.remain_num) != EOF) {
        if (strcmp(temp.train_num, train_num) == 0) {
            deleted = 1;
            continue;
        }
        tickets[i++] = temp;
    }
    fclose(fp);

    // 写入文件
    fp = fopen(FILENAME, "w");
    if (fp == NULL) {
        printf("Open file failed!\n");
        return;
    }
    for (int j = 0; j < i; j++) {
        fprintf(fp, "%s %s %s %s %.2f %d\n", tickets[j].train_num,
                                             tickets[j].start_city,
                                             tickets[j].end_city,
                                             tickets[j].start_time,
                                             tickets[j].price,
                                             tickets[j].remain_num);
    }
    fclose(fp);

    // 更新票数
    if (deleted) {
        (*num_tickets)--;
        printf("Delete ticket succeeded!\n");
    } else {
        printf("Train number not found!\n");
    }
}

// 修改车票信息
void modify_ticket(Ticket *tickets, int num_tickets) {
    // 打开文件
    FILE *fp = fopen(FILENAME, "r+");
    if (fp == NULL) {
        printf("Open file failed!\n");
        return;
    }

    // 输入车次
    char train_num[10];
    printf("Enter train number: ");
    scanf("%s", train_num);

    // 查找车票信息
    Ticket temp;
    int found = 0;
    long offset = 0;
    while (!found && fscanf(fp, "%s %s %s %s %f %d", temp.train_num, temp.start_city, 
                                       temp.end_city, temp.start_time, 
                                       &temp.price, &temp.remain_num) != EOF) {
        if (strcmp(temp.train_num, train_num) == 0) {
            found = 1;
        } else {
            offset = ftell(fp);
        }
    }

    if (!found) {
        printf("Train number not found!\n");
        fclose(fp);
        return;
    }

    // 修改车票信息
    printf("Enter new start city (current: %s): ", temp.start_city);
    scanf("%s", temp.start_city);
    printf("Enter new end city (current: %s): ", temp.end_city);
    scanf("%s", temp.end_city);
    printf("Enter new start time (current: %s): ", temp.start_time);
    scanf("%s", temp.start_time);
    printf("Enter new price (current: %.2f): ", temp.price);
    scanf("%f", &temp.price);
    printf("Enter new remain number (current: %d): ", temp.remain_num);
    scanf("%d", &temp.remain_num);

    // 写入文件
    fseek(fp, offset, SEEK_SET);
    fprintf(fp, "%s %s %s %s %.2f %d\n", temp.train_num,
                                         temp.start_city,
                                         temp.end_city,
                                         temp.start_time,
                                         temp.price,
                                         temp.remain_num);

    // 关闭文件
    fclose(fp);
    printf("Modify ticket succeeded!\n");
}

// 查询车票信息
void query_ticket(Ticket *tickets, int num_tickets) {
    // 打开文件
    FILE *fp = fopen(FILENAME, "r");
    if (fp == NULL) {
        printf("Open file failed!\n");
        return;
    }

    // 输入车次
    char train_num[10];
    printf("Enter train number: ");
    scanf("%s", train_num);

    // 查找车票信息
    Ticket temp;
    int found = 0;
    while (!found && fscanf(fp, "%s %s %s %s %f %d", temp.train_num, temp.start_city, 
                                       temp.end_city, temp.start_time, 
                                       &temp.price, &temp.remain_num) != EOF) {
        if (strcmp(temp.train_num, train_num) == 0) {
            found = 1;
            printf("Train Number: %s\n", temp.train_num);
            printf("From: %s\n", temp.start_city);
            printf("To: %s\n", temp.end_city);
            printf("Departure time: %s\n", temp.start_time);
            printf("Price: %.2f\n", temp.price);
            printf("Remain number: %d\n", temp.remain_num);
        }
    }

    if (!found) {
        printf("Train number not found!\n");
    }

    // 关闭文件
    fclose(fp);
}

// 显示车票信息
void display_tickets(Ticket *tickets, int num_tickets) {
    // 打开文件
    FILE *fp = fopen(FILENAME, "r");
    if (fp == NULL) {
        printf("Open file failed!\n");
        return;
    }

    // 读取车票信息
    Ticket temp;
    int i = 0;
    while (fscanf(fp, "%s %s %s %s %f %d", temp.train_num, temp.start_city, 
                                          temp.end_city, temp.start_time, 
                                          &temp.price, &temp.remain_num) != EOF) {
        tickets[i++] = temp;
    }
    fclose(fp);

    // 按照车次排序
    for (int j = 0; j < num_tickets-1; j++) {
        for (int k = 0; k < num_tickets-j-1; k++) {
            if (strcmp(tickets[k].train_num, tickets[k+1].train_num) > 0) {
                Ticket temp = tickets[k];
                tickets[k] = tickets[k+1];
                tickets[k+1] = temp;
            }
        }
    }

    // 显示车票信息
    printf("Train Number\tFrom\t\tTo\t\tDeparture Time\tPrice\tRemain Number\n");
    for (int j = 0; j < num_tickets; j++) {
        printf("%-10s\t%-12s\t%-12s\t%-12s\t%-.2f\t%d\n", tickets[j].train_num, 
                                                           tickets[j].start_city, 
                                                           tickets[j].end_city, 
                                                           tickets[j].start_time, 
                                                           tickets[j].price, 
                                                           tickets[j].remain_num);
    }
}

int main() {
    Ticket tickets[100];
    int num_tickets = 0;

    while (1) {
        // 显示菜单
        printf("\n");
        printf("1. Add ticket\n");
        printf("2. Delete ticket\n");
        printf("3. Modify ticket\n");
        printf("4. Query ticket\n");
        printf("5. Display tickets\n");
        printf("0. Exit\n");

        // 选择操作
        int op;
        printf("Enter operation: ");
        scanf("%d", &op);

        switch (op) {
            case 1:
                add_ticket(tickets, &num_tickets);
                break;
            case 2:
                delete_ticket(tickets, &num_tickets);
                break;
            case 3:
                modify_ticket(tickets, num_tickets);
                break;
            case 4:
                query_ticket(tickets, num_tickets);
                break;
            case 5:
                display_tickets(tickets, num_tickets);
                break;
            case 0:
                exit(0);
            default:
                printf("Invalid operation!\n");
        }
    }

    return 0;
}

注意事项：
- 本程序使用了一个全局变量 `FILENAME`，表示存储车票信息的文件名，请确保程序运行目录下有该文件并有写入权限。
- 本程序最多支持存储 100 条车票信息，可以根据需要修改代码。
- 本程序没有进行异常处理，请确保输入的数据合法。