creating a Huffman Tree

[tj720]

I need to write a program that will accept a valid text file, read it, then create a Huffman tree from the file, encode the text, then decode it to prove that my tree works. I have already written the code to create the priority queue for the tree, but when i try to actually build the tree at the end my root node isn't linked to its right or left children. Why isn't it linking like it should?

Here is the code for my "build_tree()" method:

	void build_tree()
	{
		int progress = 1;
		while(priority_list.size()>1)
		{
			char c=' ';
			Node* temp = new Node(c);
			temp->left = priority_list[priority_list.size()-1];
			priority_list.pop_back();
			temp->right=priority_list[priority_list.size()-1];
			priority_list.pop_back();
			temp->order = progress; //keeps track of which new nodes are the oldest.
			progress++;
			int left_freq=0;
			int right_freq=0;
			if(temp->left!=NULL)
				left_freq=temp->left->freq;
			if(temp->right!=NULL)
				right_freq=temp->right->freq;
			temp->freq = left_freq + right_freq;
			priority_list.push_back(temp);
			organize_priority_list();
		}
		root = priority_list[0];
		priority_list.pop_back();
	}

so i thought that once i reached the end, my priority list will only have 1 node left in it (which i tested and it does) so i could just assign the root (which is a Node pointer) to that remaining object. but when i run my print() method (which is also tested and works fine), the root doesn't have any children linked. can someone help please?