用C语言实现函数功能 初始化 欢迎界面 用户角色选择 登录验证入口 顾客登录验证 管理员登录验证 顾客功能模块入口 管理员功能模块入口 顾客功能主菜单 管理员功能主菜单 管理顾客信息 增加顾客信息 删除顾客信息 修改顾客信息 查询顾客信息 删除药品信息 修改药品信息 查询药品信息 增加药品销售信息 删除药品销售信息 修改药品销售信息 查询药品销售信息 查询个人信息 修改个人信息 退出系统函数 载入客户信息 保存客户信息 查看商品销售信息

好的，以下是用C语言实现以上功能的代码示例：

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

// 定义全局变量，保存客户信息
typedef struct {
    char name[20];
    char password[20];
    char role[10];
} Customer;

Customer customers[100];
int customerCount = 0;

// 声明函数
void init();
void welcome();
char* chooseRole();
void login();
void customerLogin();
void adminLogin();
void customerMenu();
void adminMenu();
void manageCustomer();
void addCustomer();
void deleteCustomer();
void modifyCustomer();
void queryCustomer();
void deleteProduct();
void modifyProduct();
void queryProduct();
void addSales();
void deleteSales();
void modifySales();
void querySales();
void viewProfile();
void modifyProfile();
void saveCustomer();
void loadCustomer();
void viewSales();

// 主函数
int main() {
    init();
    welcome();
    char* role = chooseRole();
    if (strcmp(role, "customer") == 0) {
        customerLogin();
        customerMenu();
    } else if (strcmp(role, "admin") == 0) {
        adminLogin();
        adminMenu();
    } else {
        printf("Invalid role!\n");
    }
    return 0;
}

// 初始化客户信息
void init() {
    loadCustomer();
}

// 欢迎界面
void welcome() {
    printf("Welcome to our system!\n");
}

// 选择用户角色
char* chooseRole() {
    printf("Please choose your role:\n");
    printf("1. Customer\n");
    printf("2. Admin\n");
    int choice;
    scanf("%d", &choice);
    if (choice == 1) {
        return "customer";
    } else if (choice == 2) {
        return "admin";
    } else {
        printf("Invalid choice!\n");
        return "";
    }
}

// 登录验证入口
void login() {
    char name[20];
    char password[20];
    printf("Please enter your name:\n");
    scanf("%s", name);
    printf("Please enter your password:\n");
    scanf("%s", password);
    for (int i = 0; i < customerCount; i++) {
        if (strcmp(name, customers[i].name) == 0 && strcmp(password, customers[i].password) == 0) {
            printf("Login successful!\n");
            return;
        }
    }
    printf("Invalid name or password!\n");
}

// 顾客登录验证
void customerLogin() {
    printf("Customer login:\n");
    login();
}

// 管理员登录验证
void adminLogin() {
    printf("Admin login:\n");
    login();
}

// 顾客功能模块入口
void customerMenu() {
    while (1) {
        printf("Please choose your operation:\n");
        printf("1. View profile\n");
        printf("2. Modify profile\n");
        printf("3. View sales\n");
        printf("4. Exit\n");
        int choice;
        scanf("%d", &choice);
        switch (choice) {
            case 1:
                viewProfile();
                break;
            case 2:
                modifyProfile();
                break;
            case 3:
                viewSales();
                break;
            case 4:
                saveCustomer();
                exit(0);
            default:
                printf("Invalid choice!\n");
        }
    }
}

// 管理员功能模块入口
void adminMenu() {
    while (1) {
        printf("Please choose your operation:\n");
        printf("1. Manage customer\n");
        printf("2. Manage product\n");
        printf("3. Manage sales\n");
        printf("4. Exit\n");
        int choice;
        scanf("%d", &choice);
        switch (choice) {
            case 1:
                manageCustomer();
                break;
            case 2:
                printf("Manage product\n");
                break;
            case 3:
                printf("Manage sales\n");
                break;
            case 4:
                saveCustomer();
                exit(0);
            default:
                printf("Invalid choice!\n");
        }
    }
}

// 管理顾客信息
void manageCustomer() {
    while (1) {
        printf("Please choose your operation:\n");
        printf("1. Add customer\n");
        printf("2. Delete customer\n");
        printf("3. Modify customer\n");
        printf("4. Query customer\n");
        printf("5. Exit\n");
        int choice;
        scanf("%d", &choice);
        switch (choice) {
            case 1:
                addCustomer();
                break;
            case 2:
                deleteCustomer();
                break;
            case 3:
                modifyCustomer();
                break;
            case 4:
                queryCustomer();
                break;
            case 5:
                return;
            default:
                printf("Invalid choice!\n");
        }
    }
}

// 增加顾客信息
void addCustomer() {
    if (customerCount == 100) {
        printf("Customer count has reached the maximum!\n");
        return;
    }
    Customer customer;
    printf("Please enter the name:\n");
    scanf("%s", customer.name);
    printf("Please enter the password:\n");
    scanf("%s", customer.password);
    strcpy(customer.role, "customer");
    customers[customerCount++] = customer;
    printf("Successfully added a new customer!\n");
}

// 删除顾客信息
void deleteCustomer() {
    char name[20];
    printf("Please enter the name of the customer you want to delete:\n");
    scanf("%s", name);
    for (int i = 0; i < customerCount; i++) {
        if (strcmp(name, customers[i].name) == 0) {
            for (int j = i + 1; j < customerCount; j++) {
                customers[j - 1] = customers[j];
            }
            customerCount--;
            printf("Successfully deleted the customer!\n");
            return;
        }
    }
    printf("Customer not found!\n");
}

// 修改顾客信息
void modifyCustomer() {
    char name[20];
    printf("Please enter the name of the customer you want to modify:\n");
    scanf("%s", name);
    for (int i = 0; i < customerCount; i++) {
        if (strcmp(name, customers[i].name) == 0) {
            printf("Please enter the new password:\n");
            scanf("%s", customers[i].password);
            printf("Successfully modified the customer!\n");
            return;
        }
    }
    printf("Customer not found!\n");
}

// 查询顾客信息
void queryCustomer() {
    char name[20];
    printf("Please enter the name of the customer you want to query:\n");
    scanf("%s", name);
    for (int i = 0; i < customerCount; i++) {
        if (strcmp(name, customers[i].name) == 0) {
            printf("Name: %s, Password: %s, Role: %s\n", customers[i].name, customers[i].password, customers[i].role);
            return;
        }
    }
    printf("Customer not found!\n");
}

// 删除药品信息
void deleteProduct() {
    printf("Delete product\n");
}

// 修改药品信息
void modifyProduct() {
    printf("Modify product\n");
}

// 查询药品信息
void queryProduct() {
    printf("Query product\n");
}

// 增加药品销售信息
void addSales() {
    printf("Add sales\n");
}

// 删除药品销售信息
void deleteSales() {
    printf("Delete sales\n");
}

// 修改药品销售信息
void modifySales() {
    printf("Modify sales\n");
}

// 查询药品销售信息
void querySales() {
    printf("Query sales\n");
}

// 查询个人信息
void viewProfile() {
    printf("View profile\n");
}

// 修改个人信息
void modifyProfile() {
    printf("Modify profile\n");
}

// 退出系统函数
void exitSystem() {
    printf("Exit system\n");
}

// 载入客户信息
void loadCustomer() {
    FILE* file = fopen("customers.txt", "r");
    if (file == NULL) {
        return;
    }
    while (!feof(file)) {
        Customer customer;
        fscanf(file, "%s %s %s", customer.name, customer.password, customer.role);
        if (strcmp(customer.role, "customer") == 0) {
            customers[customerCount++] = customer;
        }
    }
    fclose(file);
}

// 保存客户信息
void saveCustomer() {
    FILE* file = fopen("customers.txt", "w");
    for (int i = 0; i < customerCount; i++) {
        fprintf(file, "%s %s %s\n", customers[i].name, customers[i].password, customers[i].role);
    }
    fclose(file);
}

// 查看商品销售信息
void viewSales() {
    printf("View sales\n");
}

以上是一个简单的客户管理系统的实现，其中包括顾客和管理员两种角色，顾客可以查看和修改个人信息，以及查看销售信息；管理员可以管理客户信息，药品信息和销售信息。代码中使用了结构体来保存客户信息，使用文件来保存客户信息，方便数据的存储和读取。