大约有 44,000 项符合查询结果（耗时：0.0496秒） [XML]
What is the rationale for all comparisons returning false for IEEE754 NaN values?
...l compare unordered with everything, including itself.
As far as writing extra code to handle NaNs goes, it is usually possible (though not always easy) to structure your code in such a way that NaNs fall through properly, but this is not always the case. When it isn't, some extra code may be nec...
Applicatives compose, monads don't
..., perhaps to tragic effect.
The monadic version relies essentially on the extra power of (>>=) to choose a computation from a value, and that can be important. However, supporting that power makes monads hard to compose. If we try to build ‘double-bind’
(>>>>==) :: (Monad m, ...
How to vertically center a container in Bootstrap?
...rial, sans-serif;
}
WORKING DEMO.
Also, to prevent unexpected issues in extra small screens, you can reset the height of the pseudo-element to auto or 0 or change its display type to none if needed so:
@media (max-width: 768px) {
.vertical-center:before {
height: auto;
/* Or */
di...
How to add one day to a date? [duplicate]
... database. Use a JDBC driver compliant with JDBC 4.2 or later. No need for strings, no need for java.sql.* classes.
Where to obtain the java.time classes?
Java SE 8, Java SE 9, Java SE 10, and later
Built-in.
Part of the standard Java API with a bundled implementation.
Java 9 adds some minor ...
C++ : why bool is 8 bits long?
...or booleans, in a way. I seem to remember Pascal implementing sets as bit strings. That is, for the following set:
{1, 2, 5, 7}
You might have this in memory:
01100101
You can, of course, do something similar in C / C++ if you want. (If you're keeping track of a bunch of booleans, it could ...
How is “int* ptr = int()” value initialization not illegal?
...h C++11, now you want to use nullptr because it also tosses the benefit of extra compile-time checks into the mix.
– Jamin Grey
Feb 27 '13 at 1:07
3
...
What is DOCTYPE?
...
In HTML (including XHTML) as used on web pages, DOCTYPE is a string that triggers one of a few browser modes (quirks mode, standards mode, almost standards mode), depending on the exact spelling of the DOCTYPE. You want to use it to select a browser mode that best suits your page.
For...
ActiveRecord: size vs count
...many association, size will use the cached count directly, and not make an extra query at all.
class Image < ActiveRecord::Base
belongs_to :product, counter_cache: true
end
class Product < ActiveRecord::Base
has_many :images
end
> product = Product.first # query, load product into m...
When should I use a trailing slash in my URL?
...ile) when a directory is accessed, so /foo/ is /foo/index.html without the extra mess. Also, in the past, browsers would append / to the domain name, but they (Firefox, Chrome, Opera) have since changed to omit the / when accessing the homepage.
– 0b10011
Mar 7...
When to use static classes in C# [duplicate]
...ery cheap operation in most languages, so speed is not an issue. Adding an extra line of code to the consumer is a low cost for laying the foundation of a much more maintainable solution in the future. And finally, if you want to avoid creating instances, simply create a singleton wrapper of your cl...