Programming Forums > Application Development > C++

titaniumdecoy · Mar 22nd, 2006, 1:29 PM

I keep getting the error "'NULL' was not declared in this scope" in all my C++ programs. From what I understand, 0 is the equivalent of NULL, but I am wondering why NULL does not seem to work.

I am working on a LinkedList class, and am having the problem that when I try to access the last ListNode in the list, the loop does not stop cycling through memory after it has reached the last ListNode. I am trying to compare the nodes to 0 (empty nodes have been initialized to 0 because NULL does not work). What am I doing wrong? Thanks.

(Toggle Plain Text)

int LinkedList::dequeue() {
    ListNode *current = front;
    while (current->next != 0) { // What should my test condition be?
        current = current->next;
    }
    return current->value;
}

EDIT: I solved the problem, I had not initialized the front ListNode to 0.

Mar 22nd, 2006, 1:29 PM	#1
titaniumdecoy Expert Programmer Join Date: Nov 2005 Posts: 856 Rep Power: 3	'NULL' was not declared in this scope I keep getting the error "'NULL' was not declared in this scope" in all my C++ programs. From what I understand, 0 is the equivalent of NULL, but I am wondering why NULL does not seem to work. I am working on a LinkedList class, and am having the problem that when I try to access the last ListNode in the list, the loop does not stop cycling through memory after it has reached the last ListNode. I am trying to compare the nodes to 0 (empty nodes have been initialized to 0 because NULL does not work). What am I doing wrong? Thanks. (Toggle Plain Text) int LinkedList::dequeue() { ListNode current = front; while (current->next != 0) { // What should my test condition be? current = current->next; } return current->value; } int LinkedList::dequeue() { ListNode current = front; while (current->next != 0) { // What should my test condition be? current = current->next; } return current->value; } EDIT: I solved the problem, I had not initialized the front ListNode to 0. Last edited by titaniumdecoy; Mar 22nd, 2006 at 1:42 PM.

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