Returning pointer to a struct defined inside a class, multiple scope operators

my header file for a basic binary tree includes the following:

Code:

template<typename T> class Btree{ // OVERVIEW: a binary tree with flexible structure that is not sorted private: struct node { //a container object node *left; //left and right tree node *right; T *o; // pointer to object of node }; public: node *root; //pointer to the root of the tree (NULL if empty) node* insert (node *parent, T *child, int child); //MODIFIES: this //EFFECTS: creates a node that stores a pointer to the new child // and returns the pointer to the node of the new child // the integer child is either 0, for left child, // or anything else for right child // void printTree (node * root); //EFFECTS: takes the root of a tree and prints the tree's // coordinates Btree(); //ctor Btree(){} //dtor }; #include "btree.cpp"

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my .cpp looks like this, and not that it is included at the bottom of my header to avoid template compiler errors:

Code:

template <typename T> Btree<T> :: node * Btree<T>::insert (node *parent, T *child, int child) { node *np = new node; np-> o = child; np->left = NULL; np->right = NULL; if (child == 0) parent->left = np; else parent->right = np; return np; }

however, i get the following compiler error:
btree.cpp:3: error: expected constructor, destructor, or type conversion before ‘*’ token

i'm compiling on 4.1.2 of the g++ compiler

Can anyone help!?!?! http://im.cprogramming.com/images/smilies/frown.png

> node* insert (node *parent, T *child, int child);
Why does two of them has the same name ?

>Btree<T> :: node * Btree<T>::insert (node *parent, T *child, int child)
Apparently, a newer version of the compiler will you better error messages.

Quote:

Originally Posted by g++

a.cpp:34:1: error: need ‘typename’ before ‘Btree<T>::node’ because ‘Btree<T>’ is a dependent scope

The error literally instructs you what to do (I had this a while ago.. and totally ignored it thinking it meant something else!..don't do that.)

Also.. this can't be done:

Code:

Btree(); //ctor Btree(){} //dtor

THANK YOU! so helpful!

when I removed all the templates I am getting errors again. I followed what others recommend and my code looks like this:

Code:

class Btree{ // OVERVIEW: a binary tree that is not sorted private: struct node { //a container object node *left; //if the direction is straight node *right; //if a right turn is made node *parent; // points to the parent tile *t; // pointer to object of node }; public: node *root; //pointer to the root of the tree (NULL if empty) node * insert (tile *parent, tile *child, int childNum); //MODIFIES: this //EFFECTS: creates a node that stores a pointer to the new child // and returns the pointer to the node of the new child // the integer child is either 0, for left child, // or anything else for right child // for the purposes of this project, all right turns // are stored on the right subtree tile * removeAll(node *root); //EFFECTS: deletes all nodes from the tree. called in dtor Btree(); //ctor Btree(tile *o); //alternative ctor, sets root to o ~Btree(); //dtor };

and the .cpp file has this now

Code:

Btree :: node * Btree ::insert(node *parent, tile *child, int childNum) { node *np = new node; np-> t = child; np->left = NULL; np->right = NULL; if (root == NULL){ root = np; } else{ np->parent = parent; if (childNum == 0) parent->left = np; else parent->right = np; } return np; }

with this compiler error:

Quote:

btree.cpp:3: error: prototype for ‘Btree::node* Btree::insert(Btree::node*, tile*, int)’ does not match any in class ‘Btree’
btree.h:31: error: candidate is: Btree::node* Btree::insert(tile*, tile*, int)

any ideas?!

Read the error message. It says that your function prototype in line 3 of btree.cpp does not match the prototype in line 31 of the header.