C语言实现火车订票系统

实现火车订票系统的完整攻略分为以下几个步骤：

1. 设计数据库

火车订票系统需要一个数据库来存储车次信息、座位信息、乘客信息等。可以使用MySQL或者SQLite等关系型数据库。设计数据库时需要考虑信息的表结构、字段类型、约束条件等。以下是一个汽车票订购系统的数据库设计：

车次信息表：train_info
字段：train_id, start_station, end_station, start_time, end_time, total_seat

座位信息表：seat_info
字段：train_id, seat_type, seat_number, status

乘客信息表：passenger_info
字段：passenger_id, name, id_card_number, contact_phone, booking_status, order_id

2. 编写程序

编程语言选择C语言，需要用到数据库访问库mysqlclient.h。

2.1 连接数据库

使用mysql_init()函数初始化mysql结构体，然后使用mysql_real_connect()函数连接到数据库。连接到数据库之后可以使用mysql_select_db()函数选择要操作的数据库。

MYSQL *mysql;
mysql = mysql_init(NULL);
mysql_real_connect(mysql, "localhost", "root", "password", NULL, 0, NULL, 0);
mysql_select_db(mysql, "train_info");

2.2 增加车次信息

使用mysql_real_query()函数执行SQL语句，向车次信息表中增加车次信息。以下是一个增加车次信息的示例：

char *sql = "INSERT INTO train_info (train_id, start_station, end_station, start_time, end_time, total_seat) VALUES ('G102', '北京', '上海', '07:00:00', '12:30:00', 100)";
mysql_real_query(mysql, sql, (unsigned int)strlen(sql));

2.3 查询可用座位

查询可用座位需要用到座位信息表和乘客信息表。首先查询座位信息表中指定车次、指定座位类型、状态为0（未预订）的座位，然后查询乘客信息表中已预订该座位的乘客数，计算可用座位数。

以下是一个查询可用座位的示例：

char *sql = "SELECT COUNT(*) FROM seat_info WHERE train_id='G102' AND seat_type='一等座' AND status=0"
mysql_real_query(mysql, sql, (unsigned int)strlen(sql));
MYSQL_RES *result = mysql_store_result(mysql);
MYSQL_ROW row;
int available_seat;
if (result != NULL && (row = mysql_fetch_row(result)) != NULL) {
    available_seat = 100 - atoi(row[0]);
}

2.4 预订座位

预订座位需要用到座位信息表和乘客信息表。首先查询可用座位数，如果可用座位数大于等于要预订的座位数，则使用mysql_real_query()函数执行SQL语句，向座位信息表中增加座位信息，并向乘客信息表中增加乘客信息。

以下是一个预订座位的示例：

//查询可用座位数
char *sql = "SELECT COUNT(*) FROM seat_info WHERE train_id='G102' AND seat_type='一等座' AND status=0"
mysql_real_query(mysql, sql, (unsigned int)strlen(sql));
MYSQL_RES *result = mysql_store_result(mysql);
MYSQL_ROW row;
int available_seat;
if (result != NULL && (row = mysql_fetch_row(result)) != NULL) {
    available_seat = 100 - atoi(row[0]);
}

//预订座位
if (available_seat >= 2) {
    mysql_real_query(mysql, "START TRANSACTION", 17);
    char *sql1 = "INSERT INTO seat_info (train_id, seat_type, seat_number, status) VALUES ('G102', '一等座', 'A1', 1)";
    mysql_real_query(mysql, sql1, (unsigned int)strlen(sql1));
    char *sql2 = "UPDATE passenger_info SET booking_status=1, order_id=10001 WHERE passenger_id=1";
    mysql_real_query(mysql, sql2, (unsigned int)strlen(sql2));
    mysql_real_query(mysql, "COMMIT", 6);
} else {
    printf("Not enough available seats.");
}

3. 测试程序

使用编译器编译程序，运行程序测试各个功能。以下是一个测试程序的示例：

#include <stdio.h>
#include <stdlib.h>
#include <mysql/mysql.h>

int main(int argc, const char * argv[]) {

    MYSQL *mysql;
    mysql = mysql_init(NULL);
    mysql_real_connect(mysql, "localhost", "root", "password", NULL, 0, NULL, 0);
    mysql_select_db(mysql, "train_info");

    //增加车次信息
    char *sql1 = "INSERT INTO train_info (train_id, start_station, end_station, start_time, end_time, total_seat) VALUES ('G102', '北京', '上海', '07:00:00', '12:30:00', 100)";
    mysql_real_query(mysql, sql1, (unsigned int)strlen(sql1));

    //查询可用座位数
    char *sql2 = "SELECT COUNT(*) FROM seat_info WHERE train_id='G102' AND seat_type='一等座' AND status=0";
    mysql_real_query(mysql, sql2, (unsigned int)strlen(sql2));
    MYSQL_RES *result = mysql_store_result(mysql);
    MYSQL_ROW row;
    int available_seat;
    if (result != NULL && (row = mysql_fetch_row(result)) != NULL) {
        available_seat = 100 - atoi(row[0]);
        printf("Available seat: %d\n", available_seat);
    }

    //预订座位
    if (available_seat >= 2) {
        mysql_real_query(mysql, "START TRANSACTION", 17);
        char *sql3 = "INSERT INTO seat_info (train_id, seat_type, seat_number, status) VALUES ('G102', '一等座', 'A1', 1)";
        mysql_real_query(mysql, sql3, (unsigned int)strlen(sql3));
        char *sql4 = "UPDATE passenger_info SET booking_status=1, order_id=10001 WHERE passenger_id=1";
        mysql_real_query(mysql, sql4, (unsigned int)strlen(sql4));
        mysql_real_query(mysql, "COMMIT", 6);
        printf("Booking success.\n");
    } else {
        printf("Not enough available seats.\n");
    }

    mysql_close(mysql);
    return 0;
}