Question

我的班级extPersonType继承自其他3个班级。程序编译时没有错误，但由于某种原因，字符串relation和phoneNumber不会显示。我要求的所有其他信息都有。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启动它们

    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)
{
}

您不应忘记在构造函数

中分配/初始化变量

此外，这是推荐，但我不认为继承是必要的。你应该使用作文。

class extPersonType
{
 private:
   string relation; 
   string phoneNumber;

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

Answer 2

你应该把它称为

my_home.print();

你可能对它的声明方式感到困惑：

void extPersonType::print(){ <..> }

这里extPersonType::部分告诉编译器函数是类的一部分。当您调用该函数时，您已经为该类的特定对象（在您的情况下为my_home）调用它，因此您不应该使用类名。

Answer 3

您实际上并未初始化类成员变量。您需要执行以下操作来初始化relation和phoneNumber成员：

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),
      relation(relation), phoneNumber(phoneNumber)  // <== init mmebers
{
}

我怀疑您可能需要对addressType，personType和dateType基类构造函数执行类似操作。

当我调用print（）函数时，为什么赢得了我的字符串输出？

3 个答案: