Circular Double Linked List - Logic in Operator=

This is a discussion on Circular Double Linked List - Logic in Operator= within the C++ Programming forums, part of the General Programming Boards category; Hello folks, I am working ona a circular double linked list and trying to overload the operator= operand but I ...

  1. #1
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    Exclamation Circular Double Linked List - Logic in Operator=

    Hello folks, I am working ona a circular double linked list and trying to overload the operator= operand but I think my logic is false.

    It takes in a linked list and inserts the data into the current linked list.

    I believe this is not a deep copy

    Code:
    template <class T>
    CList<T>& CList<T>::operator=(const CList<T> &a){
    	if(this!=&a){
    		if(a.curr_){
    			Node<T> *nn_ = a.curr_;
    			do{		
    				nn_ = nn_->next_;
    				insert(nn_->data_);
    			}while(nn_!=a.curr_);
    		}
    	}
    	return *this;
    }

  2. #2
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    Usually the result of using operator= is that both sides would have the same value. What you are trying to do is append, which is more along the lines of what operator+= does.

    If you want to make it a real operator=, then clear your current list before adding the other elements.

    The only thing I see wrong with that code if it was for operator+= is that I think it skips the insertion of a.curr_. If it was an operator+= I wouldn't check for self-assignment either.

  3. #3
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    Any tips on how to do this?

  4. #4
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    I'm not sure what you mean. Those are the tips on how to do that. Is there something in particular that you'd like more information on?

  5. #5
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    How to remove every node of the list.
    I came up with this code but I come up with an unhandled windows32 exception upon runtime.

    Code:
    template <class T>
    bool CList<T>::remove(){
    	
    	if(this->isempty()){
    		return false;
    	}
    	else if(!this->isempty()&&curr_){
    		Node<T> *prev_;
    		Node<T> *next_;
    		
    		if(curr_->next_==curr_&&curr_->prev_==curr_){
    			delete curr_;
    			curr_ = NULL;
    		}
    		else{
    		prev_ = curr_->prev_;
    		next_ = curr_->next_;
    		
    		delete curr_;
    		
    		prev_->next_ = next_;
    		next_->prev_ = prev_;
    
    		curr_ = next_;
    
    		return true;
    		}
    	}
    	else return false;
    }
    It deletes the node pointed at by curr_
    Last edited by INFERNO2K; 09-30-2006 at 10:03 AM.

  6. #6
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    I don't see anything particularly wrong with that remove function (except that if there is only one node in the list the function exits without returning a value). I assume you have a clear function that keeps calling it while it returns true, which also should be ok.

    You'll have to find out more information on when, where and why the exception occurs. A debugger would be most helpful for that. You can also make a small test program that writes to cerr after each step if you can't use the debugger.

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