StackOverflow2013

Note that there are some explanatory texts on larger screens.

plurals

PO
primarykey
Id
5905397
data
AcceptedAnswerId
0
AnswerCount
0
ClosedDate
CommentCount
1
CommunityOwnedDate
CreationDate
2011-05-05T23:56:25.167
FavoriteCount
0
LastActivityDate
2017-07-19T13:11:57.053
LastEditDate
2017-07-19T13:11:57.053
LastEditorUserId
576911
OwnerUserId
576911
ParentId
5905204
PostTypeId
2
Score
29
ViewCount
0
LastEditorDisplayName
text
Body
<pre><code>m.rehash(pow(2,x)); </code></pre> if <code>pow(2, x)</code> is the number of buckets you want preallocated. You can also: <pre><code>m.reserve(pow(2,x)); </code></pre> but now <code>pow(2, x)</code> is the number of elements you are planning on inserting. Both functions do nothing but preallocate buckets. They don't insert any elements. And they are both meant to be used exactly for your use case. Note: You aren't guaranteed to get exactly <code>pow(2, x)</code> buckets. Some implementations will use only a number of buckets which is a power of 2. Other implementations will use only a prime number of buckets. Still others will use only a subset of primes for the number of buckets. But in any case, the implementation should accept your hint at the number of buckets you desire, and then internally round up to its next acceptable number of buckets. Here is the precise wording that the latest (N4660) uses to specify the argument to <code>rehash</code>: <code>a.rehash(n)</code> : Postconditions: <code>a.bucket_count() >= a.size() / a.max_load_factor() and a.bucket_count() >= n</code>. This postcondition ensures that <code>bucket()_count() >= n</code>, and that <code>load_factor()</code> remains less than or equal to <code>max_load_factor()</code>. Subsequently <code>reserve(n)</code> is defined in terms of <code>rehash(n)</code>: <code>a.reserve(n)</code> : Same as <code>a.rehash(ceil(n / a.max_load_factor()))</code>.
Tags
Title
singulars
PostAcceptedAnswerId
1. This table or related slice is empty.
PostParentId
1. POPre-allocating buckets in a C++ std::unordered_map
 singulars
 PostTypePostTypeId
 PTQuestion
PostTypePostTypeId
1. PTAnswer
UserLastEditorUserId
1. USHoward Hinnant
UserOwnerUserId
1. USHoward Hinnant
plurals
PostLinksPostIdRelatedPostId
1. This table or related slice is empty.
PostLinksRelatedPostIdPostId
1. This table or related slice is empty.
PostsAcceptedAnswerId
1. POPre-allocating buckets in a C++ std::unordered_map
 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
 VTUpMod
2. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
3. VO
 singulars
 PostPostId
 PO
 UserUserId
 This table or related slice is empty.
 VoteTypeVoteTypeId
 VTUpMod
CommentsPostId
1. This table or related slice is empty.

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.