How can I delete a node from anywhere in a linked list?

[GaryWalker96]

I know how to remove a node from the front of a singly linked list, but I have no idea how to remove one from any arbitrary location.

In my specific problem, I continue to pass an integer value x into each node in the linked list. I can add and delete, but there is a function I need to write where if I've identified two x's that are the same, I delete the other instance.

[wizebin]

You can crawl your list, find the previous node, and have that previous node connect to the next node, then delete the current node. It's a bit easier in a doubly linked list because you can simply connect the nodes together then perish.

[48T7M4Gy]

Move to the particular node and amend the links to suit and then delete it.

I'd help with the second paragraph of yours if I understood it especially because your code about it is currently a mystery.

[GaryWalker96]

Thanks for the response, I'll go ahead and try that real quick and report back

[GaryWalker96]

This is what I've been trying to do so far

void Singly_Linked_List :: add_unique_age_to_the_front(int x)
{
	//Insert a new age to the front of the singly linked list

	Node* addUnique=head;

	if(!test_age_contained_in_singly_linked_list(x))  //Call the test age function for a case where it is not true no matter what
		{
			
		    Node* newNode2;
			newNode2= new Node(x);
			newNode2->next=head;
		     head=newNode2; 
		
		}
		
	
}

void Singly_Linked_List :: remove_age_from_singly_linked_list(int x)
{
    Node* removeAge=head;
	Node* prevNode=NULL;

	while(removeAge!=NULL)
	{
		if(test_age_contained_in_singly_linked_list(x))
		{
			prevNode->next=removeAge->next;
			delete removeAge;
		}

		prevNode=removeAge;
		removeAge=removeAge->next;

	}

}

[GaryWalker96]

For some reason, related to my dynamic memory allocation, I get an unhandled exception error on line 29.

[48T7M4Gy]

Please show us main() etc plus everything in one listing so we can run it and replicate the error.

[dhayden]

Based on add_unique_age_to_the_front(), it looks like test_age_contained_in_singly_linked_list() returns true if the argument is anywhere in the list. But that isn't what you want to test in remove_age_from_singly_linked_list(). You want to remove a specific node if that node has the age.

Your error at line 29 occurs because test_age_contaned_in_singly_lionked_list() returns true on the first call, but in that case, prevNode is NULL, so prevNode->next generates a memory error.

When you remove the node, don't forget to delete it so you don't leak the memory.

[GaryWalker96]

Thank you so much! That makes alot of sense. How can I fix this error? Do I need to change my test_age function?

[dhayden]

Change line 26 to check whether removeAge contains the age x. Since you haven't shown the declaration of class Node, I can't say exactly how to do this.

Then you'll have to deal with the possbility that prevNode is NULL. In that case you're removing from the head of the list.

[dhayden]

Change line 27 to check whether removeAge is the age in question.

Also deal with the case where prevNode==NULL. That means that you're removing from the head of the list.