void Show_InOder_BST(BSTNode* root)
{
assert(root != NULL);
std::stack<BSTNode*> st;
st.push(root);
bool tag=true;while (!st.empty())
{while (tag && st.top()->leftchild != NULL){st.push(st.top()->leftchild);}BSTNode* tmp;tmp = st.top();st.pop();printf("%d ", tmp->data);if (tmp->rightchild != NULL){st.push(tmp->rightchild);tag = true;}else{tag = false;}
}
}