Uncertainties about OOP and the struct Keyword

class NodeType { 
 public: 
    int info; 
    NodeType* link; 
};

I came across this when learning about linked list, and as a beginner, at line 4, pointer link is an object of class NodeType, this interpretation is definitely wrong, so can somebody please explain what does this line mean? I don’t recall learning this when I am interacting with the concept of OOP.

struct NodeType 
{ 
    int info; 
    struct NodeType* link; 
}; 

I take that this structure declaration here is of the same as the class declared above, so my second question is, why is there a second struct keyword at line 4? Can the keyword be removed? Is this the phenomenon called nested struct?

>Solution :

Yes, the two snippets are the same.

why is there a second struct keyword at line 4?

It’s called an elaborated type specifier (a type with struct prepended to it, or class/union/enum; the definition class NodeType {} doesn’t count as one).

It’s useless here and can be removed. It’s only useful when a struct is mentioned for the first time, so the compiler doesn’t know it’s a struct yet.

In this regard C++ is different from C, where you must prepend struct every time to refer to a struct.

[is] pointer link is an object of class NodeType?

No, an object of class NodeType would be NodeType link;, but then it wouldn’t be a pointer.

You could say that link is an object of type NodeType * (a pointer to NodeType).