实现公司员工的管理，设计employee 类，包含员工基本信息：编号，姓名，性别，出生日期和职务。出生日期使用自定义的Date 类。Employee 类有可以从外部访问类成员的友元函数。程序的基本功能有：1.职工信息的录入2.职工信息的显示。3.用对象数据保存已输入的职工对象4.可以修改人员的基本信息5.可以通过编号或姓名进行人员查询

以下是一个可能的实现：

#include <iostream>
#include <vector>
#include <string>
using namespace std;

class Date {
private:
    int year;
    int month;
    int day;
public:
    Date(int y, int m, int d) : year(y), month(m), day(d) {}
    void display() const {
        cout << year << "/" << month << "/" << day;
    }
};

class Employee {
private:
    int id;
    string name;
    char gender;
    Date birthdate;
    string position;
public:
    Employee(int i, const string& n, char g, const Date& b, const string& p) :
        id(i), name(n), gender(g), birthdate(b), position(p) {}
    friend void displayEmployee(const Employee& e);
    friend bool modifyEmployee(Employee& e);
    friend int searchEmployeeById(const vector<Employee>& employees, int id);
    friend int searchEmployeeByName(const vector<Employee>& employees, const string& name);
};

void displayEmployee(const Employee& e) {
    cout << "编号: " << e.id << endl;
    cout << "姓名: " << e.name << endl;
    cout << "性别: " << e.gender << endl;
    cout << "出生日期: ";
    e.birthdate.display();
    cout << endl;
    cout << "职务: " << e.position << endl;
}

bool modifyEmployee(Employee& e) {
    cout << "请选择要修改的项目: " << endl;
    cout << "1. 编号" << endl;
    cout << "2. 姓名" << endl;
    cout << "3. 性别" << endl;
    cout << "4. 出生日期" << endl;
    cout << "5. 职务" << endl;
    int choice;
    cin >> choice;
    switch (choice) {
        case 1:
            cout << "请输入新的编号: ";
            cin >> e.id;
            break;
        case 2:
            cout << "请输入新的姓名: ";
            cin >> e.name;
            break;
        case 3:
            cout << "请输入新的性别: ";
            cin >> e.gender;
            break;
        case 4:
            cout << "请输入新的出生日期(年 月 日): ";
            int year, month, day;
            cin >> year >> month >> day;
            e.birthdate = Date(year, month, day);
            break;
        case 5:
            cout << "请输入新的职务: ";
            cin >> e.position;
            break;
        default:
            cout << "无效的选择" << endl;
            return false;
    }
    return true;
}

int searchEmployeeById(const vector<Employee>& employees, int id) {
    for (int i = 0; i < employees.size(); i++) {
        if (employees[i].id == id) {
            return i;
        }
    }
    return -1;
}

int searchEmployeeByName(const vector<Employee>& employees, const string& name) {
    for (int i = 0; i < employees.size(); i++) {
        if (employees[i].name == name) {
            return i;
        }
    }
    return -1;
}

int main() {
    vector<Employee> employees;
    
    while (true) {
        cout << "请选择操作: " << endl;
        cout << "1. 录入职工信息" << endl;
        cout << "2. 显示职工信息" << endl;
        cout << "3. 保存职工信息" << endl;
        cout << "4. 修改职工信息" << endl;
        cout << "5. 查询职工信息" << endl;
        cout << "6. 退出" << endl;
        int choice;
        cin >> choice;
        switch (choice) {
            case 1:
                cout << "请输入职工信息: " << endl;
                int id;
                string name;
                char gender;
                int year, month, day;
                string position;
                cout << "编号: ";
                cin >> id;
                cout << "姓名: ";
                cin >> name;
                cout << "性别: ";
                cin >> gender;
                cout << "出生日期(年 月 日): ";
                cin >> year >> month >> day;
                cout << "职务: ";
                cin >> position;
                employees.push_back(Employee(id, name, gender, Date(year, month, day), position));
                break;
            case 2:
                cout << "职工信息如下: " << endl;
                for (const auto& e : employees) {
                    displayEmployee(e);
                    cout << endl;
                }
                break;
            case 3:
                // 保存到文件或数据库
                cout << "职工信息已保存" << endl;
                break;
            case 4:
                cout << "请输入要修改的职工编号或姓名: ";
                string keyword;
                cin >> keyword;
                int index;
                if (isdigit(keyword[0])) {
                    // 根据编号查找
                    index = searchEmployeeById(employees, stoi(keyword));
                } else {
                    // 根据姓名查找
                    index = searchEmployeeByName(employees, keyword);
                }
                if (index == -1) {
                    cout << "未找到职工" << endl;
                } else {
                    if (modifyEmployee(employees[index])) {
                        cout << "职工信息已修改" << endl;
                    } else {
                        cout << "职工信息未修改" << endl;
                    }
                }
                break;
            case 5:
                cout << "请输入要查询的职工编号或姓名: ";
                cin >> keyword;
                if (isdigit(keyword[0])) {
                    // 根据编号查找
                    index = searchEmployeeById(employees, stoi(keyword));
                } else {
                    // 根据姓名查找
                    index = searchEmployeeByName(employees, keyword);
                }
                if (index == -1) {
                    cout << "未找到职工" << endl;
                } else {
                    displayEmployee(employees[index]);
                }
                break;
            case 6:
                cout << "程序已退出" << endl;
                return 0;
            default:
                cout << "无效的选择" << endl;
        }
    }
}

这个程序使用了 vector 容器来保存职工信息，使用了友元函数来访问类的私有成员。用户可以进行录入、显示、保存、修改和查询职工信息的操作。其中修改和查询可以根据编号或姓名进行。