在类中创建一个向量，然后在函数中使用类对象不起作用

Question

我有一堂课Employees。我试图让用户插入和删除员工，但它不起作用。向量的大小应为 500。

class Employees{
public:
    int maxx = 500;
    vector<string> Surname;
    vector<string> FirstName;
    vector<string> birthdate;
    int vacation[500];
public:
    Employees() : Surname(500) {}
};

这是插入的函数，但打印向量的元素根本不起作用：

void Process(Employees ZZ){

    string dateyear;
    string datemonth;
    string dateday;
    int dateyear1;
    int datemonth1;
    int dateday1;
    int Realage;
    int Vacationi = 0;

    for(int i = 0; i < 500; i++) {

        string s;
        cin >> s;
        string d;
        cin >> d;
        string c;
        cin >> c;

        ZZ.Surname.push_back(s);
        ZZ.FirstName.push_back(d);
        ZZ.birthdate.push_back(c);

        cout << endl << ZZ.Surname[1] << endl;
    }

现在是删除函数，如果我输入一个字符串然后在向量中搜索它然后获取他的索引然后删除，但是向量不会更新任何值。

void DeleteEmployee(Employees ZZ){

    cout<< endl <<  ZZ.Surname[1] << endl ;

    for (int i = 0; i < ZZ.Surname.size(); i++){
        cout << ZZ.Surname[i] ;
    }
    cout << " delete employee";
    string delete1;
    cin >> delete1;

    auto it = std::find(ZZ.Surname.begin(), ZZ.Surname.end(), delete1);
    if (it == ZZ.Surname.end())
    {
        cout<< " name not in vector "  << endl;
    }
    else
    {
        //auto index = distance(Names.begin(), find(Names.begin(), Names.end(), old_name_)));
        //ZZ.Surname.erase(ZZ.Surname.begin()+index) ;
    }
}

这是主要功能，向量的值也不打印：

int main()
{
    Employees ZZ;
    Process(ZZ);
    DeleteEmployee(ZZ);
    cout << "fyccck";

    for (int i = 0; i < ZZ.Surname.size(); i++){
        cout << ZZ.Surname[i] ;
    }
}

Answer 1

这段代码有很多问题。但是您要问的特定问题是由您的函数传递Employees 对象按值 引起的，因此复制 以及您对copy 没有反映在main() 的original 对象中。

您需要更改参数以通过引用传递Employees对象：

void Process(Employees &ZZ)
void DeleteEmployee(Employees &ZZ)

---

话虽如此，总体而言，代码的整体设计并不好。向量没有正确保持同步，因此您使用的向量比实际需要的多，1 个 vector 就足够了。而Process() 和DeleteEmployee() 应该是Employees 类的成员，而不是单独的函数。而且它们都在访问Surname 向量的边界。

我建议从头开始完全重写代码，例如更像这样：

struct Employee{
    string Surname;
    string FirstName;
    string BirthDate;
    int Vacation;

    string DisplayName() const { return Surname + ", " + FirstName; }
};

class Employees{
public:
    static const int maxx = 500;
    vector<Employee> employees;

    Employees() { employees.reserve(maxx); }

    bool Add(const Employee &e);
    bool Delete(string Surname, string FirstName);
};

bool Employees::Add(const Employee &e) {
    if (employees.size() < maxx) {
        employees.push_back(e);
        return true;
    }
    return false;
}

bool Employees::Delete(string Surname, string FirstName) {
    auto it = std::find_if(employees.begin(), employees.end(),
        [&](const Employee &e){
            return e.Surname == Surname && e.FirstName == FirstName;
        }
    );
    if (it != employees.end()) {
        employees.erase(it);
        return true;
    }
    return false;
}

int main()
{
    Employees ZZ;

    for(int i = 0; i < Employees::maxx; ++i) {
        Employee e;
        cin >> e.Surname;
        cin >> e.FirstName;
        cin >> e.BirthDate;
        e.Vacation = 0;//cin >> e.Vacation;

        ZZ.Add(e);

        cout << endl << e.DisplayName() << endl;
    }

    cout << " delete employee";
    string Surname, FirstName;
    if (cin >> Surname >> FirstName) {
        if (ZZ.Delete(Surname, FirstName)) {
            cout << " name deleted from vector " << endl;
        } else {
            cout << " name not in vector " << endl;
        }
    }

    cout << "fyccck";

    for (auto &e : ZZ.employees) {
        cout << e.DisplayName() << endl;
    }

    return 0;
}