大约有 40,000 项符合查询结果（耗时：0.0400秒） [XML]
How should one use std::optional?
...
@Rapptz Line 256: union storage_t { unsigned char dummy_; T value_; ... } Line 289: struct optional_base { bool init_; storage_t<T> storage_; ... } How is that not "a T and a bool"? I completely agree the implementation is very tricky an...
Is short-circuiting logical operators mandated? And evaluation order?
... function, at least one of the arguments needs to be a class (or struct or union) or an enum, or a reference to one of those. Being POD means that you can use memcpy on it.
– Derek Ledbetter
Mar 12 '09 at 21:45
...
What's the best CRLF (carriage return, line feed) handling strategy with Git?
...t diff=html
*.css text
*.js text
*.sql text
*.csproj text merge=union
*.sln text merge=union eol=crlf
*.docx diff=astextplain
*.DOCX diff=astextplain
# absolute paths are ok, as are globs
/**/postinst* text eol=lf
# paths that don't start with / are treated relative to the .gita...
Why does Java's hashCode() in String use 31 as a multiplier?
... for 31 since 33 is not a prime:
Of the remaining
four, I'd probably select P(31), as it's the cheapest to calculate on a RISC
machine (because 31 is the difference of two powers of two). P(33) is
similarly cheap to calculate, but it's performance is marginally worse, and
33 is composit...
I need to store postal codes in a database. How big should the column be?
...nce a block on one side of the street. To find a broader region, you would select the first half of the postal code. Having this information in a separate table really won't help anything and would be more complicated to maintain.
– RevNoah
Dec 2 '13 at 17:08
...
What's the $unwind operator in MongoDB?
...oDB employs an "NoSQL" approach to data storage, so perish the thoughts of selects, joins, etc. from your mind. The way that it stores your data is in the form of documents and collections, which allows for a dynamic means of adding and obtaining the data from your storage locations.
That being sai...
Can someone give an example of cosine similarity, in a very simple, graphical way?
...e1)
counter2 = Counter(iterable2)
all_items = set(counter1.keys()).union(set(counter2.keys()))
vector1 = [counter1[k] for k in all_items]
vector2 = [counter2[k] for k in all_items]
return vector1, vector2
def cosim(v1, v2):
dot_product = sum(n1 * n2 for n1, n2 in zip(v1, v2)...
Facebook database design?
...O_INCREMENT=2 DEFAULT CHARSET=utf8;
Friends of Friends Query:
(
select friend_id
from friends
where user_id = 1
) union (
select distinct ff.friend_id
from
friends f
join friends ff on ff.user_id = f.friend_id
where f.use...
What is Full Text Search vs LIKE
... can enable support for leading wildcards by pre-compiling suffix trees in selected fields.
Other features typical of full-text search are
lexical analysis or tokenization—breaking a
block of unstructured text into
individual words, phrases, and
special tokens
morphological
analysis, or stemmi...
Why does Clojure have “keywords” in addition to “symbols”?
...t constructs are needed. Couldn't Clojure have created something with the union of the capabilities of both Keyword and Symbol?
– user73774
Oct 16 '09 at 19:57
25
...