Thread: Binary search tree

You may try a more sanitized wording, to help you understand better what your are trying to achieve.

Perhaps something along the following lines...

Code:

typedef struct TreeNode TreeNode;
struct TreeNode{
    int val;
    TreeNode *left;
    TreeNode *right;
};

typedef struct StackNode StackNode;
struct StackNode {
    TreeNode  *treenode;
    StackNode *prev;
};

/* this is not really needed, but I followed your example */
typedef struct Stack Stack;
struct Stack {
    int nelems;
    StackNode *top;
};

Please note that forward declarations with typedef's are optional in your case (for example, it's not that you are implementing a library with opaque objects), but they help in writing shorter code later on.

Then define the basic operations for your stack. For example...

Code:

void        stack_push( Stack *stack, const TreeNode *treenode );
TreeNode   *stack_pop( Stack *stack );
int         stack_empty( const Stack *stack );
void        stack_destroy( Stack *stack );

Finally define your stack, lets say...

Code:

...
int main( void )
{
    Stack s = {0, NULL};
    ...

and you should be good to go.

PS. Btw, hi everybody, this is my first post in the forum.