Question

#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <string>

using namespace std;

class car{
    private:
    string color;
    int mileage;
    int topSpeed;
    int numGears;
    public:
};

class carNode{
    private:
    car Car;
    carNode *next;
    friend class carLinkedlist;
};

class carLinkedlist{
    public:
    carLinkedlist();
    ~carLinkedlist();
    bool empty() const;
    void addtolist(const car& theCar);
    const carNode* getHead();
    private:
    carNode* head;
};

const carNode* carLinkedlist::getHead(){
    return head;
} 

void car::setDetails(const string color,const int mileage,const int topSpeed,const int numGears){
    this->color = color;
    this->mileage = mileage;
    this->topSpeed = topSpeed;
    this->numGears = numGears;
}

carLinkedlist::carLinkedlist(){
    head = NULL;
}

carLinkedlist::~carLinkedlist(){
    // what to do here
}

bool carLinkedlist::empty() const{
    if (head==NULL)
        return true;
    return false;
}

void carLinkedlist::addtolist(const car& theCar){
    if (empty()){
        head = new carNode;
        head->Car = theCar;
        head->next = NULL;
    }
    else{
        carNode* temp = new carNode;
        temp->Car = theCar;
        temp->next = NULL;
        head->next = temp;
    }
}

int main(){
    car car1;
    car1.setDetails("red",40,140,5);
    const car& carr1 = car1;
    car car2;
    car2.setDetails("black",30,220,5);
    const car& carr2 = car2;
    carLinkedlist carList;
    carList.addtolist(carr1);
    carList.addtolist(carr2);
    //cout << car1.getColor() << endl;
    cout << (carList.getHead())->next->Car.getColor() << endl;
    return 0;
}

此代码在第二行最后一行抛出错误，而且Car都是私有的。我可以创建一个getCar函数来访问Car的值，但是对于受保护的next，该怎么做，我该如何访问它的值。

P.S。我出于类似的原因制作了getHead函数，即访问头部但我无法通过函数访问下一个函数，因为接下来将会有下一个＆gt;受保护。另外请验证我是否应该制作getCar函数或执行其他操作。

Answer 1

一种解决方案是成为next成员public。

另一种解决方案是在link_to内添加carNode函数：

class carNode
{
  public:  
    void link_to(carNode& cn)
    {
        next = &cn;
    }
  private:
  //...
};

如何访问链接列表中的下一个c ++

1 个答案: