c++ - 为什么当我调用 print() 函数时我的字符串不输出？

Question

我的类 extPersonType 是从其他 3 个类继承的。程序编译没有错误，但由于某种原因，字符串 relation 和 phoneNumber 没有显示。我要求的所有其他信息都可以。我的问题在哪里？

class extPersonType: public personType, public dateType, public addressType
{
public:
extPersonType(string relation = "", string phoneNumber = "", string address = "", string city = "", string state = "", int zipCode = 55555, string first = "", string last = "", 
    int month = 1, int day = 1, int year = 0001)
    : addressType(address, city, state, zipCode),  personType(first, last), dateType (month, day, year)
{
}
void print() const;

private:
string relation; 
string phoneNumber;
};

void extPersonType::print() const
{
cout << "Relationship: " << relation << endl;
cout << "Phone Number: " << phoneNumber << endl;
addressType::print();
personType::print();
dateType::printDate();
}



/*******
MAIN PROGRAM
*******/

int main()
{
extPersonType my_home("Friend", "555-4567", "5142 Wyatt Road", "North Pole", "AK", 99705, "Jesse", "Alford", 5, 24, 1988);
my_home .extPersonType::print();
      return 0;
}

Answer 1

那是因为你没有在任何地方初始化它们

    extPersonType(string relation = "", string phoneNumber = "", string address = "", string city = "", string state = "", int zipCode = 55555, string first = "", string last = "", int month = 1, int day = 1, int year = 0001)
        : relation (relation), phoneNumber (phoneNumber)// <<<<<<<<<<<< this is missing
           addressType(address, city, state, zipCode),  personType(first, last), dateType (month, day, year)
{
}

你不应该忘记在构造函数中分配/初始化你的变量

此外，这是推荐，但我真的不认为这里需要继承。你应该使用合成。

class extPersonType
{
 private:
   string relation; 
   string phoneNumber;

   addressType address;
   personType person_name;
   dateType date; // birthday ?
}