内部类和外部成员的访问
我一直认为内部类可以访问其外部类中的所有数据，但有代码：
template<class T>
class Vector
{
template<class T>
friend
std::ostream& operator<<(std::ostream& out, const Vector<T>& obj);
private:
T** myData_;
std::size_t myIndex_;
std::size_t mySize_;
public:
Vector():myData_(nullptr),
myIndex_(0),
mySize_(0)
{ }
Vector(const Vector<T>& pattern);
void insert(const T&);
Vector<T> makeUnion(const Vector<T>&)const;
Vector<T> makeIntersection(const Vector<T>&)const;
class Iterator : public std::iterator<std::bidirectional_iterator_tag,T>
{
private:
T** itData_;
public:
Iterator()//<<<<<<<<<<<<<------------COMMENT
{ /*HERE I'M TRYING TO USE ANY MEMBER FROM Vector<T> AND I'M GETTING ERR SAYING:
ILLEGAL CALL OF NON-STATIC MEMBER FUNCTION*/}
Iterator(T** ty)
{
itData_ = ty;
}
Iterator operator++()
{
return ++itData_;
}
T operator*()
{
return *itData_[0];
}
bool operator==(const Iterator& obj)
{
return *itData_ == *obj.itData_;
}
bool operator!=(const Iterator& obj)
{
return *itData_ != *obj.itData_;
}
bool operator<(const Iterator& obj)
{
return *itData_ < *obj.itData_;
}
};
typedef Iterator iterator;
iterator begin()const
{
assert(mySize_ > 0);
return myData_;
}
iterator end()const
{
return myData_ + myIndex_;
}
};
请参阅标记为 COMMENT 的行。
那么我可以在内部类中使用外部类的成员吗？
不用担心命名，它不是向量，而是集合。
谢谢。
I always thought that internal class has access to all data in its external class but having code:
template<class T>
class Vector
{
template<class T>
friend
std::ostream& operator<<(std::ostream& out, const Vector<T>& obj);
private:
T** myData_;
std::size_t myIndex_;
std::size_t mySize_;
public:
Vector():myData_(nullptr),
myIndex_(0),
mySize_(0)
{ }
Vector(const Vector<T>& pattern);
void insert(const T&);
Vector<T> makeUnion(const Vector<T>&)const;
Vector<T> makeIntersection(const Vector<T>&)const;
class Iterator : public std::iterator<std::bidirectional_iterator_tag,T>
{
private:
T** itData_;
public:
Iterator()//<<<<<<<<<<<<<------------COMMENT
{ /*HERE I'M TRYING TO USE ANY MEMBER FROM Vector<T> AND I'M GETTING ERR SAYING:
ILLEGAL CALL OF NON-STATIC MEMBER FUNCTION*/}
Iterator(T** ty)
{
itData_ = ty;
}
Iterator operator++()
{
return ++itData_;
}
T operator*()
{
return *itData_[0];
}
bool operator==(const Iterator& obj)
{
return *itData_ == *obj.itData_;
}
bool operator!=(const Iterator& obj)
{
return *itData_ != *obj.itData_;
}
bool operator<(const Iterator& obj)
{
return *itData_ < *obj.itData_;
}
};
typedef Iterator iterator;
iterator begin()const
{
assert(mySize_ > 0);
return myData_;
}
iterator end()const
{
return myData_ + myIndex_;
}
};
See line marked as COMMENT.
So can I or I can't use members from external class while in internal class?
Don't bother about naming, it's not a Vector it's a Set.
Thank you.
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评论（2）
您需要将外部类的实例传递给内部类。换句话说，您的 Iterator 类必须有一个指向 Vector 实例的引用（或指针）。执行此操作的最佳方法是让
Iterator构造函数获取对Vector的引用。You need to pass an instance of the external class to the internal class. In other words, your
Iteratorclass must have a reference (or pointer) to an instance ofVectorhandy. The best way to do this is to have theIteratorconstructor take a reference to aVector.您无法从 C++ 中的周围类访问字段或方法！
You cannot access fields or methods from the sourrounding class in C++!