c++ - Overloading operator++ to find and return successor node of binary search tree -

this relevant portion of code involving overloading operator++ find , return successor node of binary search tree. i've tested tree itself, , forms correctly, , cout's correctly using inorder traversal function.

but can't life of me figure out i'm doing wrong overloading operator++. i've tried many different versions, , latest one, nextinordersuccessor, returns successor when /not/ called within overloaded operator++

this, along fact i've made multiple version of operator++, lead me believe i'm handling actual overloaded operator wrong. can offer insight?

wcbst tree class. curr, being incremented, node. that's why returned node.

void wcbst::write_to_file() { //  ofstream outfile;     outfile.open("wcbst.txt");     curr = minvalue(root);     (int = 0; < count;i++)     {          cout << '{' << curr->data.first << ',' << curr->data.second << "}\n";         outfile << '{' << curr->data.first << ',' << curr->data.second << "}\n";         ++curr;      } node *wcbst::operator++()  {     return nextinordersuccessor(root, curr); } node* wcbst::nextinordersuccessor(node* root, node* tofind) {       node* successor = null;     if (tofind->right) {         successor = tofind->right;         while (successor->left) {             successor = successor->left;         }     }     else {         while (root) {             if (tofind->data < root->data) {                 successor = root;                 root = root->left;             }             else if (tofind->data > root->data) {                 root = root->right;             }             else {                 break;             }         }     }     return successor; }