Question

I created a program which, so far, creates a binary tree of nodes for a Huffman coding program. For some reason, when the debugger gets to the point where it tests if the two children equal Null or not (so there an actual character on the tree and not just a parent), the program freezes. Codes is an array of the codes for each object comprising of Code structs which have two member variables.

void Huff::traverse(Node* root, vector<Code>* code, string code_base){
    if(root->childL == NULL && root->childR == NULL){ //stops here
        Code c;
        c.content = root->litteral;
        c.symbol = code_base;
        code->push_back(c);
    }else{
        if (root->childL != NULL)
            traverse(root->childL, code, code_base + '0');
        if (root->childR != NULL)
            traverse(root->childR, code, code_base + '1');
    }
}

The function which calls this one is (it’s called towards the end):

vector<Code>* Huff::compress(){
    //-------GETTING WEIGHTS/FREQUENCIES------
    vector<Node *>* nodes = new vector<Node*>; // Vector of nodes for later use
    map<char, int>* freq = new map<char, int>; //  Map to find weight of nodes
    for(unsigned int i = 0; i < content.length(); i++)
        (*freq)[content[i]]++; 
    CopyTo copyto(nodes); //sets vector<Node*> to copy to 
    for_each(freq->begin(), freq->end(), copyto); // Copies 
    delete freq;
    vector<Node *>::iterator beg = nodes->begin();

    //-------SETTING UP TO BUILD TREE------
    if(nodes->size() % 2 == 1){ //makes sure there are an even number of nodes
        Node* fill = new Node;
        fill->set_node(0, '*', NULL, NULL);
        nodes->push_back(fill);
    }
    huff_sort(nodes); // sort nodes by weight

    //-------BUILDING TREE------
    while(nodes->size() != 1){ //Sorts nodes by weight and then removes two of them and replaces them with one
        int w= (**beg).weight + (**(beg+1)).weight;
        Node* p = new Node;
        p->set_node(w, '*', *nodes->begin(), *(nodes->begin()+1)); //making it the parent node of the two lowest nodes
        nodes->erase(nodes->begin(), nodes->begin()+2);
        unsigned int i = 0;
        while(w > (*nodes)[i]->weight && i <= nodes->size()){ //finds where to insert the parent node based on weight
            i++;
        }
        if(i > nodes->size()) //if it needs to be inserted at the end
            nodes->push_back(p);
        else
            nodes->insert(nodes->begin()+i, p);
        delete p;
    }

    //-------TRAVERSING TREE------
    Node* root = (*nodes)[0];
    delete nodes;
    vector<Code>* codes;
    traverse(root, codes , "");
    delete root;
    return codes;
}

Note: The while loop before the traverse tree block of code is where the tree is created

Answer 1

You need to say delete nodes; after you call traverse. What you have right now makes root point to NULL before you call traverse.