大约有 43,000 项符合查询结果（耗时：0.0645秒） [XML]
System.currentTimeMillis() vs. new Date() vs. Calendar.getInstance().getTime()
In Java, what are the performance and resource implications of using
8 Answers
8
...
How can I check if multiplying two numbers in Java will cause an overflow?
I want to handle the special case where multiplying two numbers together causes an overflow. The code looks something like this:
...
ValueError: numpy.dtype has the wrong size, try recompiling
I just installed pandas and statsmodels package on my python 2.7
When I tried "import pandas as pd", this error message comes out.
Can anyone help? Thanks!!!
...
What exactly do “IB” and “UB” mean?
I've seen the terms "IB" and "UB" used several times, particularly in the context of C++. I've tried googling them, but apparently those two-letter combinations see a lot of use. :P
...
What is std::move(), and when should it be used?
...
Wikipedia Page on C++11 R-value references and move constructors
In C++11, in addition to copy constructors, objects can have move constructors.
(And in addition to copy assignment operators, they have move assignment operators.)
The move constructor is used instead...
What are the disadvantages to declaring Scala case classes?
...
First the good bits:
Everything immutable by default
Yes, and can even be overridden (using var) if you need it
Getters automatically defined
Possible in any class by prefixing params with val
Decent toString() implementation
Yes, very useful, but doable by hand on any class if nece...
Is it possible to make a type only movable and not copyable?
...ntation.
To answer the question you didn't ask... "what's up with moves and copy?":
Firstly I'll define two different "copies":
a byte copy, which is just shallowly copying an object byte-by-byte, not following pointers, e.g. if you have (&usize, u64), it is 16 bytes on a 64-bit computer, ...
How do you determine what technology a website is built on? [closed]
Quite often I come across a nice looking or functional website, and wonder what technology was used to create it. What techniques are available to figure out what a
particular website was built with?
...
Can Git hook scripts be managed along with the repository?
...hooks/ . However, those scripts are not propagated when people do a clone and they are not version controlled.
11 Answer...
What is this crazy C++11 syntax ==> struct : bar {} foo {};?
...
First, we'll take a bog-standard abstract UDT (User-Defined Type):
struct foo { virtual void f() = 0; }; // normal abstract type
foo obj;
// error: cannot declare variable 'obj' to be of abstract type 'foo'
Let's also recall that we can instantiate...