使用c++单链表实现校园卡信息的管理，属性包括：卡号（字符型），姓名（字符型），余额（整型），密码（六位字符型）

以下是一个简单的实现，包括添加、删除、修改、查找和展示功能：

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

#define MAX_NAME_LENGTH 20
#define PASSWORD_LENGTH 6

typedef struct student_card {
    char id[20]; // 卡号
    char name[MAX_NAME_LENGTH]; // 姓名
    int balance; // 余额
    char password[PASSWORD_LENGTH + 1]; // 密码
    struct student_card *next; // 下一个节点
} StudentCard;

// 添加校园卡信息
void add_student_card(StudentCard **head) {
    StudentCard *new_card = (StudentCard *)malloc(sizeof(StudentCard));
    printf("请输入卡号：");
    scanf("%s", new_card->id);
    printf("请输入姓名：");
    scanf("%s", new_card->name);
    printf("请输入余额：");
    scanf("%d", &new_card->balance);
    printf("请输入密码：");
    scanf("%s", new_card->password);
    new_card->next = NULL;

    // 将新节点插入链表头部
    if (*head == NULL) {
        *head = new_card;
    } else {
        new_card->next = *head;
        *head = new_card;
    }
}

// 删除校园卡信息
void delete_student_card(StudentCard **head, char *id) {
    StudentCard *current = *head;
    StudentCard *prev = NULL;

    while (current != NULL) {
        if (strcmp(current->id, id) == 0) {
            if (prev == NULL) {
                *head = current->next;
            } else {
                prev->next = current->next;
            }
            free(current);
            printf("删除成功！\n");
            return;
        }
        prev = current;
        current = current->next;
    }

    printf("找不到该卡号对应的信息！\n");
}

// 修改校园卡信息
void modify_student_card(StudentCard *head, char *id) {
    StudentCard *current = head;

    while (current != NULL) {
        if (strcmp(current->id, id) == 0) {
            printf("请输入新的姓名：");
            scanf("%s", current->name);
            printf("请输入新的余额：");
            scanf("%d", &current->balance);
            printf("请输入新的密码：");
            scanf("%s", current->password);
            printf("修改成功！\n");
            return;
        }
        current = current->next;
    }

    printf("找不到该卡号对应的信息！\n");
}

// 查找校园卡信息
void search_student_card(StudentCard *head, char *id) {
    StudentCard *current = head;

    while (current != NULL) {
        if (strcmp(current->id, id) == 0) {
            printf("卡号：%s，姓名：%s，余额：%d，密码：%s\n", current->id, current->name, current->balance, current->password);
            return;
        }
        current = current->next;
    }

    printf("找不到该卡号对应的信息！\n");
}

// 展示所有校园卡信息
void show_student_cards(StudentCard *head) {
    StudentCard *current = head;

    printf("卡号\t\t姓名\t\t余额\t\t密码\n");
    while (current != NULL) {
        printf("%s\t\t%s\t\t%d\t\t%s\n", current->id, current->name, current->balance, current->password);
        current = current->next;
    }
}

int main() {
    StudentCard *head = NULL;
    int choice;
    char id[20];

    while (1) {
        printf("\n1.添加学生卡信息\n2.删除学生卡信息\n3.修改学生卡信息\n4.查找学生卡信息\n5.展示学生卡信息\n6.退出\n");
        printf("请选择操作：");
        scanf("%d", &choice);

        switch (choice) {
            case 1:
                add_student_card(&head);
                break;
            case 2:
                printf("请输入要删除的卡号：");
                scanf("%s", id);
                delete_student_card(&head, id);
                break;
            case 3:
                printf("请输入要修改的卡号：");
                scanf("%s", id);
                modify_student_card(head, id);
                break;
            case 4:
                printf("请输入要查找的卡号：");
                scanf("%s", id);
                search_student_card(head, id);
                break;
            case 5:
                show_student_cards(head);
                break;
            case 6:
                printf("再见！\n");
                exit(0);
            default:
                printf("请输入正确的选项！\n");
                break;
        }
    }

    return 0;
}