大约有 44,000 项符合查询结果（耗时：0.0744秒） [XML]
How does collections.defaultdict work?
...re precisely, it's an arbitrary "callable" object, which includes function and type objects). For the first example, default items are created using int(), which will return the integer object 0. For the second example, default items are created using list(), which returns a new empty list object....
Simple calculations for working with lat/lon and km distance?
Is there a simple calculation I can do which will convert km into a value which I can add to a lat or lon float to calculate a bounding box for searches? It doesn't need to be completely accurate.
...
How to pass optional arguments to a method in C++?
... else
do_something_else();
}
you can call myfunc in both ways and both are valid
myfunc(10); // Mode will be set to default 0
myfunc(10, 1); // Mode will be set to 1
share
|
impr...
What's the difference between integer class and numeric class in R
...ouble precision floating point numbers) and integer. R will automatically convert between the numeric classes when needed, so for the most part it does not matter to the casual user whether the number 3 is currently stored as an integer or as a double. Most math is done using double precision, so ...
What's the difference between IQueryable and IEnumerable
...like LINQ-to-SQL to exist because they can parse the expression tree and convert it into equivalent SQL. And because the provider doesn't need to execute until the IQueryable is enumerated (it implements IEnumerable<T>, after all), it can combine multiple query operators (in the above exampl...
Can I call a base class's virtual function if I'm overriding it?
Say I have classes Foo and Bar set up like this:
7 Answers
7
...
What is the difference between an int and a long in C++?
... (an answer by example) with some of the details below regarding the C++ standard. The draft for C++0x is at open-std.org/JTC1/SC22/WG21/docs/papers/2008/n2798.pdf and it is marked up so you can see the differences between it and the last rev.
– Patrick Johnmeyer
...
Performance of Arrays vs. Lists
...u need to have a list/array of integers which you need iterate frequently, and I mean extremely often. The reasons may vary, but say it's in the heart of the inner most loop of a high volume processing.
...
Is it possible to print a variable's type in standard C++?
... update to a very old question: Print variable type in C++.
The accepted (and good) answer is to use typeid(a).name(), where a is a variable name.
Now in C++11 we have decltype(x), which can turn an expression into a type. And decltype() comes with its own set of very interesting rules. For exam...
Why use double indirection? or Why use pointers to pointers?
...
Yes, and if you ever lose track of one of your pointers, here's a pointer: pointerpointer.com
– Andrew Cheong
Aug 21 at 0:50
...