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，性命，出生日期和职务等。出生日期使用自定义的date类，employee类有可能从外部访问类成员的友元函数，程序基本功能有：1职工信息的录入，2职工信息的显示3.用对象数组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

好的，下面是一个简单的实现：

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

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

class Employee {
public:
    Employee(int id, string n, char s, Date b, string p) : 
        id(id), name(n), sex(s), birth(b), position(p) {}
    void display() {
        cout << "编号：" << id << endl;
        cout << "姓名：" << name << endl;
        cout << "性别：" << sex << endl;
        cout << "出生日期：";
        birth.display();
        cout << "职务：" << position << endl;
    }
    friend void modify(Employee& e);
    friend class ManagementSystem;
private:
    int id;
    string name;
    char sex;
    Date birth;
    string position;
};

void modify(Employee& e) {
    cout << "请输入修改后的信息：" << endl;
    cout << "编号：";
    cin >> e.id;
    cout << "姓名：";
    cin >> e.name;
    cout << "性别：";
    cin >> e.sex;
    cout << "出生日期（格式为yyyy-mm-dd）：";
    int year, month, day;
    char dash;
    cin >> year >> dash >> month >> dash >> day;
    Date new_birth(year, month, day);
    e.birth = new_birth;
    cout << "职务：";
    cin >> e.position;
}

class ManagementSystem {
public:
    ManagementSystem() : num(0) {}
    void input() {
        cout << "请输入员工信息：" << endl;
        int id;
        string name;
        char sex;
        cout << "编号：";
        cin >> id;
        cout << "姓名：";
        cin >> name;
        cout << "性别：";
        cin >> sex;
        cout << "出生日期（格式为yyyy-mm-dd）：";
        int year, month, day;
        char dash;
        cin >> year >> dash >> month >> dash >> day;
        Date birth(year, month, day);
        string position;
        cout << "职务：";
        cin >> position;
        Employee e(id, name, sex, birth, position);
        employees[num++] = e;
    }
    void displayById(int id) {
        for (int i = 0; i < num; i++) {
            if (employees[i].id == id) {
                employees[i].display();
                return;
            }
        }
        cout << "未找到该编号对应的员工" << endl;
    }
    void displayByName(string name) {
        for (int i = 0; i < num; i++) {
            if (employees[i].name == name) {
                employees[i].display();
                return;
            }
        }
        cout << "未找到该姓名对应的员工" << endl;
    }
    void modifyById(int id) {
        for (int i = 0; i < num; i++) {
            if (employees[i].id == id) {
                modify(employees[i]);
                return;
            }
        }
        cout << "未找到该编号对应的员工" << endl;
    }
    void modifyByName(string name) {
        for (int i = 0; i < num; i++) {
            if (employees[i].name == name) {
                modify(employees[i]);
                return;
            }
        }
        cout << "未找到该姓名对应的员工" << endl;
    }
private:
    Employee employees[100];
    int num;
};

int main() {
    ManagementSystem ms;
    while (true) {
        cout << "请选择操作：" << endl;
        cout << "1.录入员工信息" << endl;
        cout << "2.查询员工信息（按编号）" << endl;
        cout << "3.查询员工信息（按姓名）" << endl;
        cout << "4.修改员工信息（按编号）" << endl;
        cout << "5.修改员工信息（按姓名）" << endl;
        cout << "6.退出程序" << endl;
        int choice;
        cin >> choice;
        switch (choice) {
        case 1:
            ms.input();
            break;
        case 2:
            int id;
            cout << "请输入编号：";
            cin >> id;
            ms.displayById(id);
            break;
        case 3:
            string name;
            cout << "请输入姓名：";
            cin >> name;
            ms.displayByName(name);
            break;
        case 4:
            int modify_id;
            cout << "请输入编号：";
            cin >> modify_id;
            ms.modifyById(modify_id);
            break;
        case 5:
            string modify_name;
            cout << "请输入姓名：";
            cin >> modify_name;
            ms.modifyByName(modify_name);
            break;
        case 6:
            return 0;
        default:
            cout << "输入错误，请重新选择" << endl;
        }
    }
    return 0;
}

注意，为了方便起见，这里的员工信息只保存在了程序运行期间，如果程序结束后再次运行，之前录入的员工信息就会丢失。如果需要实现永久保存员工信息的功能，可以将员工信息写入文件中，或者使用数据库等技术。