CODEWITHSUNDEEP
c++
Random_Nerd
Random_Nerd

Reputation: 25

Can a private Structure(defined in a class) not be used as Return type for a function belonging to same class?

I am working on a BST. The relevant code is given below:- This is the class definition:-

class BST
{

private:
    struct Leaf
    {
      int val;
      int count;
      Leaf *left,*right;
    };


Leaf *root;  // This is unique for entire class;

public:
   BST()    // Constructor for BST
    {
      root = NULL;
    }

    void Insert(); // Insert in the BST
    Leaf* InsertNode(Leaf *pos,Leaf *node);  // Recursive and Consize function to Insert the node,extention of Insert func
    void Search(); // Search in the BST
    bool SearchNode(Leaf *pos,int val); // Recursive and Consize function to Search the node,extention of Search func
    int Count(Leaf *Node);  // Count the children of a Node
    void Print();  // Print the BST
    void Inorder(Leaf *Node,int indent);
    void Delete(); // Delete a node in BST
    Leaf* DeleteNode(Leaf *pos,int val);  // Recursive and Consize function to Delete the node,extention of Delete func


};

This is the definition of the Insert function:-

Leaf* BST::InsertNode(Leaf *pos,Leaf *node)
{
    if(pos == NULL)
    {
      return node;
    }
    if(pos->val > node->val)
        pos->left = InsertNode(pos->left,node);
    if(pos->val < node->val)
        pos->right = InsertNode(pos->right,node);   

    return pos;
}

I am getting the compilation error:-

bst.cpp(81): error C2143: syntax error : missing ';' before '*'
bst.cpp(81): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
bst.cpp(82): error C4430: missing type specifier - int assumed. Note: C++ does not support default-int
bst.cpp(82): error C2556: 'int *BST::InsertNode(BST::Leaf *,BST::Leaf *)' : overloaded function differs only by return type from 'BST::Leaf *BST::InsertNode(BST::Leaf *,BST::Leaf *)'

The error is still present even if I make declarion of Structure public. The error disappears only when I declare the struct outside class.

Can someone please explain what is the reason behind this?

Upvotes: 1

Views: 144

Answers (1)

juanchopanza
juanchopanza

Reputation: 227418

The issue is not access control, but rather scoping. Leaf is defined in BST, so its name is in the BST scope:

BST::Leaf* BST::InsertNode(BST::Leaf *pos, BST::Leaf *node)

Now, being a private type of BST places some limitations on how non-friends can access the type. They won't be able to say

BST::Leaf* leaf = foo.InsertNode(bar, baz);

but they can say

auto leaf = foo.InsertNode(bar, baz);

On the surface it looks like BST::Leaf should be public.

Upvotes: 1

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