compile error in pointer return

Question

I have the BST class same as in this thread

BST.hpp

template<class T> 
class BinarySearchTree
{
 private:
  struct tree_node
  {
    tree_node* left;
    tree_node* right;
    T data;

    tree_node( const T & thedata, tree_node * l = NULL, tree_node * r = NULL )
            : data( thedata ), left( l ), right( r ) { }
  };
tree_node* root;

public:
  //some functions
private:
  struct tree_node* minFunc( tree_node** node);
};

I was trying to return a pointer from the function as done in this thread.

the definition of minFunc is in the same BST.hpp file

template <class T>
struct tree_node* BST<T>::minFunc(tree_node** node)
{
tree_node* current = *node;
while(current->left != NULL)
{
    current = current->left;
}
return current;
}

Unable to figure out the compile errors:

error C2143: syntax error : missing ';' before '*'

error C2065: 'T' : undeclared identifier

error C2955: 'BST' : use of class template requires template argument list

error C2509: 'minFunc' : member function not declared in 'BST'

all these pointing to the definition

@BlackBear There's no missing ;, the compiler is being misleading. — cnicutar
– cnicutar, Commented May 29, 2011 at 10:38
@Node, since its a templated class, all the code is in same .hpp file — Kaushik Acharya
– Kaushik Acharya, Commented May 29, 2011 at 13:31

cnicutar · Accepted Answer · 2011-05-29 10:37:40Z

2

My best guess is that struct tree_node is not visible. It's probably not declared / declared inside some class.

answered May 29, 2011 at 10:37

cnicutar

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1 Comment

Kaushik Acharya Over a year ago

its a private member of the class BST and the entire code is in .hpp file. Is it still a problem?

BЈовић · Accepted Answer · 2011-05-30 05:38:28Z

1

Change this declaration :

struct tree_node* minFunc( tree_node** node);

into this

tree_node* minFunc( tree_node** node);

Change it's definition accordingly.

Double pointer is a sure sign of bad design
Did you include a header defining struct tree_node?

EDIT

The definition should be

template <class T>
typename BST<T>::tree_node* BST<T>::minFunc(tree_node** node)
{
tree_node* current = *node;
while(current->left != NULL)
{
    current = current->left;
}
return current;
}

by the way, take a note that the method minFunc is private and cant access it outside of the class

edited May 30, 2011 at 5:38

answered May 29, 2011 at 11:03

BЈовић

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4 Comments

Kaushik Acharya Over a year ago

removing struct gives C4430 on the definition. @2. I have put everything in same .hpp file.

BЈовић Over a year ago

@Kaushik Did you put the definition of tree_node before class BinarySearchTree?

Kaushik Acharya Over a year ago

definition of tree_node is put inside class BinarySearchTree. I have put the code in the thread.

Kaushik Acharya Over a year ago

correct. 1. I missed the typename in the function definition. 2. Regarding private member, my intention is similar to link this thread.

slashmais · Accepted Answer · 2011-05-29 10:38:27Z

0

treenode is a private struct in BST - you cannot access it outside BST

answered May 29, 2011 at 10:38

slashmais

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