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, May 29 '11 at 10:38
@Node, since its a templated class, all the code is in same .hpp file — Kaushik Acharya, May 29 '11 at 13:31

score 2 · Answer 1 · answered May 29 '11 at 10:37

2

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

answered May 29 '11 at 10:37

cnicutar

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its a private member of the class BST and the entire code is in .hpp file. Is it still a problem? – Kaushik Acharya May 29 '11 at 13:33

BЈовић · Accepted Answer · 2011-05-30T05:38:28.190

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 '11 at 05:38

answered May 29 '11 at 11:03

BЈовић

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removing struct gives C4430 on the definition. @2. I have put everything in same .hpp file. – Kaushik Acharya May 29 '11 at 13:39
@Kaushik Did you put the definition of tree_node before class BinarySearchTree? – BЈовић May 29 '11 at 15:00
definition of tree_node is put inside class BinarySearchTree. I have put the code in the thread. – Kaushik Acharya May 30 '11 at 01:40
correct. 1. I missed the **typename** in the function definition. 2. Regarding private member, my intention is similar to [link](http://stackoverflow.com/questions/5373905/why-does-this-search-function-return-a-pointer-to-a-pointer) this thread. – Kaushik Acharya May 30 '11 at 13:42

score 0 · Answer 3 · answered May 29 '11 at 10:38

0

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

answered May 29 '11 at 10:38

slashmais

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compile error in pointer return

3 Answers3