StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

PO
primarykey
Id
20058830
data
AcceptedAnswerId
0
AnswerCount
0
ClosedDate
CommentCount
6
CommunityOwnedDate
CreationDate
2013-11-18T21:58:43.727
FavoriteCount
0
LastActivityDate
2013-11-18T21:58:43.727
LastEditDate
LastEditorUserId
0
OwnerUserId
256148
ParentId
20057773
PostTypeId
2
Score
0
ViewCount
0
LastEditorDisplayName
text
Body
The short answer: Yes, <code>b->Next->Previous</code> is fine -- it's a <code>struct Node*</code>, just like the right hand side <code>b->Previous</code>. I think that your error lies with the handling of <code>Count</code>: It is incremented by <code>Add()</code>, but <code>Remove()</code> doesn't decrement it. In fact, as the list itself only needs to know whether it is empty or not, you can remove it and instead see if <code>a.First == NULL</code>. (Your <code>a.Count == 1</code> test can likewise be replaced with <code>a.First != NULL && a.First->Next == NULL</code> test.) If you're promising <code>Count</code> in you API, you can add it back when you've got the list itself working. The same "remove-then-add-back" might be useful with <code>Total</code>. Think of both of these as caches. An even better solution would be to implement a circular list: <pre><code>struct List { Node Anchor; //... }; List Create() { List l; l.Anchor.Next = l.Anchor.Previous = &l; return l; } bool IsEmpty(List const* l) { // Both or neither point at 'l'. assert((l->Anchor.Next == l) == (l->Anchor.Previous == l)); return l->Anchor.Next == l; } // Add a node 'n' to some list after 'ln'. void AddAfter(Node* n, Node* ln) { n->Previous = ln; n->Next = ln->Next; n->Next->Previous = n->Previous->Next = n; } Node* Remove(Node* n) { n->Previous->Next = n->Next; n->Next->Previous = n->Previous; n->Next = n->Previous = n; // nice and proper return x; } </code></pre> Now you longer need special cases for empty lists. I let <code>Remove()</code> return the node itself, to make it easy to either move nodes between lists (<code>AddAfter(Remove(somenode), &otherlist.Anchor)</code>) or remove and delete notes (<code>free(Remove(somenode))</code>). One wart here is that my <code>Anchor</code> node now wastes space for data that never will be used -- but that is easily fixable.
Tags
Title
singulars
PostAcceptedAnswerId
1. This table or related slice is empty.
PostParentId
1. POUsing malloc to create a linked list
 singulars
 PostTypePostTypeId
 PTQuestion
PostTypePostTypeId
1. PTAnswer
UserLastEditorUserId
1. This table or related slice is empty.
UserOwnerUserId
1. USsverkerw
plurals
PostLinksPostIdRelatedPostId
1. This table or related slice is empty.
PostLinksRelatedPostIdPostId
1. This table or related slice is empty.
PostsAcceptedAnswerId
1. POUsing malloc to create a linked list
 singulars
 PostTypePostTypeId
 PTQuestion
PostsParentIdCreationDate
1. This table or related slice is empty.
VotesPostIdCreationDate
1. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTAcceptedByOriginator
CommentsPostId

Querying!

Guidance

A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.