Question

我有这堂课：

#include <iostream>
#include <string>
#include <vector>
#include <memory>

using namespace std;

class person
{
public:
    person(string name, string surname):_name(name), _surname(surname){}
    virtual ~person(){}
    void print()
    { cout  << _name << ' ' << _surname << endl
        << "mother: " << _mother->get_name() << ' ' << _mother->get_surname() << endl
        << "father: " << _father->get_name() << ' ' << _father->get_surname() << endl; 
    }
    string get_name(){return _name;}
    string get_surname(){return _surname;}

    void set_parents(person &mother, person &father)
    {
        _mother = unique_ptr<person>(&mother);
        _father = unique_ptr<person>(&father);
    }
private:
    string _name, _surname;
    unique_ptr<person> _mother, _father;
};

然后是主要功能：

int main()
{
    vector<unique_ptr<person> > people;
    vector<unique_ptr<person> >::iterator iter;

    people.push_back(unique_ptr<person>(new person("Marisa", "Miller")));
    people.push_back(unique_ptr<person>(new person("Andrew", "Clark")));
    people.push_back(unique_ptr<person>(new person("Thomas", "Clark")));
    people.push_back(unique_ptr<person>(new person("Elisa",  "Clark")));
    people.push_back(unique_ptr<person>(new person("Edward",  "Drake")));
    people.push_back(unique_ptr<person>(new person("Jhon",  "Drake")));

    // here is the problem:
    people.at(2).set_parents(???)

    for(iter = people.begin(); iter != people.end(); ++iter)
    {
        (*iter)->print();
    }

    return 0;
}

通过指针，我将定义以下族谱：

[Marisa Miller]     [Andrew Clark]
        |                   |
        +---------+---------+
                  |
                  +--------------[Thomas Clark]
                  |
                  +--------------[Elisa Clark]      [Edward Drake]
                                       |                   |
                                       +---------+---------+
                                                 |
                                           [Jhon Drake]

问题是：如何将指针（_mother和_father，通过get_parents(...)函数）设置为向量中包含的前一个元素？ get_parents()函数也可以定义为：

void get_parents(person* mother, person* father)

或

void get_parents(unique_ptr<person> mother, unique_ptr<person> father)

感谢您的任何建议

Answer 1

有一个唯一的指针，因此指针始终只在一个地方。您有超过1个引用（在向量中，可能在Person中，如果它是父亲或母亲）。

您可能希望查看使用共享指针和弱指针： http://en.cppreference.com/w/cpp/memory/shared_ptr http://en.cppreference.com/w/cpp/memory/weak_ptr

Answer 2

person不应该拥有_mother和_father。

这可能更好：

// ...
private:
  std::string _name, _surname;
  person *_mother;
  person *_father;
};  // class person

现在，如果你保留std::vector<std::unique_ptr<person>> people;（即容器拥有其元素），你可以写：

void person::set_parents(person &mother, person &father)
{
  _mother = &mother;
  _father = &father;
}

people[2]->set_parents(*people[0], *people[1]);
people[3]->set_parents(*people[0], *people[1]);
people[5]->set_parents(*people[3], *people[4]);

同时修复person::print成员函数（如果父项缺失则崩溃）。

vector <unique_ptr <myclass>＆gt;之间的指针分子

2 个答案: