用C语言设计一个学生一卡通账户系统 主要功能：开户、注销、存款、查询、修改个人信息 系统功能说明：用户信息存在一个二进制或文本文件中，个人账户信息包括：卡号、姓名、身份证号或学号、手机号码、专业、登录密码(字母、数字的组合，至少8-16位

好的，下面是一个简单的学生一卡通账户系统的 C 语言代码，包括开户、注销、存款、查询和修改个人信息等功能：

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

#define MAX_USERS 100  // 最大用户数
#define FILE_NAME "users.txt"  // 存储用户信息的文件名

struct User {
    int card_number;  // 卡号
    char name[20];  // 姓名
    char id_number[20];  // 身份证号或学号
    char phone_number[20];  // 手机号码
    char major[20];  // 专业
    char password[20];  // 登录密码
    double balance;  // 余额
};

struct User users[MAX_USERS];  // 存储所有用户的结构体数组
int num_users = 0;  // 当前用户数

// 从文件中读取所有用户信息到内存中
void read_users() {
    FILE *fp = fopen(FILE_NAME, "rb");
    if (fp == NULL) {
        return;
    }
    num_users = 0;
    while (fread(&users[num_users], sizeof(struct User), 1, fp) == 1) {
        num_users++;
    }
    fclose(fp);
}

// 将所有用户信息写入文件
void write_users() {
    FILE *fp = fopen(FILE_NAME, "wb");
    if (fp == NULL) {
        printf("Unable to open file.\n");
        exit(1);
    }
    for (int i = 0; i < num_users; i++) {
        fwrite(&users[i], sizeof(struct User), 1, fp);
    }
    fclose(fp);
}

// 根据卡号查找用户在数组中的下标
int find_user_by_card_number(int card_number) {
    for (int i = 0; i < num_users; i++) {
        if (users[i].card_number == card_number) {
            return i;
        }
    }
    return -1;
}

// 开户
void create_account() {
    if (num_users >= MAX_USERS) {
        printf("No more users can be created.\n");
        return;
    }
    struct User user;
    printf("Please enter your name: ");
    scanf("%s", user.name);
    printf("Please enter your ID number or student ID: ");
    scanf("%s", user.id_number);
    printf("Please enter your phone number: ");
    scanf("%s", user.phone_number);
    printf("Please enter your major: ");
    scanf("%s", user.major);
    printf("Please enter your login password (at least 8-16 characters, consisting of letters and numbers): ");
    scanf("%s", user.password);
    while (strlen(user.password) < 8 || strlen(user.password) > 16) {
        printf("Password must be at least 8-16 characters long, consisting of letters and numbers. Please enter again: ");
        scanf("%s", user.password);
    }
    // 生成唯一的卡号
    user.card_number = num_users + 1;
    user.balance = 0;
    users[num_users++] = user;
    printf("Account created successfully. Your card number is %d.\n", user.card_number);
    write_users();
}

// 注销
void delete_account() {
    int card_number;
    printf("Please enter your card number: ");
    scanf("%d", &card_number);
    int index = find_user_by_card_number(card_number);
    if (index == -1) {
        printf("User not found.\n");
        return;
    }
    printf("Are you sure you want to delete your account? (y/n) ");
    char choice;
    scanf(" %c", &choice);
    if (choice == 'y' || choice == 'Y') {
        for (int i = index; i < num_users - 1; i++) {
            users[i] = users[i + 1];
        }
        num_users--;
        printf("Account deleted successfully.\n");
        write_users();
    } else {
        printf("Account not deleted.\n");
    }
}

// 存款
void deposit() {
    int card_number;
    printf("Please enter your card number: ");
    scanf("%d", &card_number);
    int index = find_user_by_card_number(card_number);
    if (index == -1) {
        printf("User not found.\n");
        return;
    }
    double amount;
    printf("Please enter the amount to be deposited: ");
    scanf("%lf", &amount);
    if (amount <= 0) {
        printf("Invalid amount.\n");
        return;
    }
    users[index].balance += amount;
    printf("Deposit successful. Your current balance is %.2lf.\n", users[index].balance);
    write_users();
}

// 查询
void inquire() {
    int card_number;
    printf("Please enter your card number: ");
    scanf("%d", &card_number);
    int index = find_user_by_card_number(card_number);
    if (index == -1) {
        printf("User not found.\n");
        return;
    }
    printf("Name: %s\n", users[index].name);
    printf("ID number or student ID: %s\n", users[index].id_number);
    printf("Phone number: %s\n", users[index].phone_number);
    printf("Major: %s\n", users[index].major);
    printf("Balance: %.2lf\n", users[index].balance);
}

// 修改个人信息
void modify() {
    int card_number;
    printf("Please enter your card number: ");
    scanf("%d", &card_number);
    int index = find_user_by_card_number(card_number);
    if (index == -1) {
        printf("User not found.\n");
        return;
    }
    printf("Please enter your new name (or press enter to keep the old name): ");
    char name[20];
    scanf("%s", name);
    if (strlen(name) > 0) {
        strcpy(users[index].name, name);
    }
    printf("Please enter your new ID number or student ID (or press enter to keep the old ID number or student ID): ");
    char id_number[20];
    scanf("%s", id_number);
    if (strlen(id_number) > 0) {
        strcpy(users[index].id_number, id_number);
    }
    printf("Please enter your new phone number (or press enter to keep the old phone number): ");
    char phone_number[20];
    scanf("%s", phone_number);
    if (strlen(phone_number) > 0) {
        strcpy(users[index].phone_number, phone_number);
    }
    printf("Please enter your new major (or press enter to keep the old major): ");
    char major[20];
    scanf("%s", major);
    if (strlen(major) > 0) {
        strcpy(users[index].major, major);
    }
    printf("Personal information modified successfully.\n");
    write_users();
}

int main() {
    read_users();
    int choice;
    do {
        printf("\n1. Create account\n");
        printf("2. Delete account\n");
        printf("3. Deposit\n");
        printf("4. Inquire\n");
        printf("5. Modify personal information\n");
        printf("6. Exit\n");
        printf("Please select an operation (1-6): ");
        scanf("%d", &choice);
        switch (choice) {
            case 1:
                create_account();
                break;
            case 2:
                delete_account();
                break;
            case 3:
                deposit();
                break;
            case 4:
                inquire();
                break;
            case 5:
                modify();
                break;
            case 6:
                printf("Goodbye!\n");
                break;
            default:
                printf("Invalid choice.\n");
                break;
        }
    } while (choice != 6);
    return 0;
}

注意，由于本程序是一个简单的练习示例，没有进行严格的输入验证和错误处理。在实际开发中，需要根据实际情况增加更多的错误处理和安全性保护。