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M_PI works with math.h but not with cmath in Visual Studio
I am using Visual Studio 2010. I have read that in C++ it is better to use <cmath> rather than <math.h> .
7...
Why can't I initialize non-const static member or static array in class?
...s allowed In-class Initialization?
The answer is hidden in Bjarne's quote read it closely,
"C++ requires that every object has a unique definition. That rule would be broken if C++ allowed in-class definition of entities that needed to be stored in memory as objects."
Note that only static con...
How is this fibonacci-function memoized?
... in Haskell is by-need: when a value is needed, it is calculated, and kept ready in case it is asked for again. If we define some list, xs=[0..] and later ask for its 100th element, xs!!99, the 100th slot in the list gets "fleshed out", holding the number 99 now, ready for next access.
That is wha...
Maintain the aspect ratio of a div with CSS
... Wow epic solution. Can't believe this was staring me in the face. I've already used these units for some font sizing can't believe it didn't occur to me to use them for this. Also just realised I can replace a good chunk of my JS stylesheet interactions. :)
– azariah
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Select by partial string from a pandas DataFrame
... select by partial string from a pandas DataFrame?
This post is meant for readers who want to
search for a substring in a string column (the simplest case)
search for multiple substrings (similar to isin)
match a whole word from text (e.g., "blue" should match "the sky is blue" but not "bluejay")
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What characters are allowed in an email address?
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Watch out! There is a bunch of knowledge rot in this thread (stuff that used to be true and now isn't).
To avoid false-positive rejections of actual email addresses in the current and future world, and from anywhere in the world, you need to know at least the high-level concept...
Which kind of pointer do I use when?
...ightweight solution if your resource offers reference-counted management already and you want to adopt it to the RAII principle. This one was not adopted by the standard.
Unique ownership:
Boost also has a scoped_ptr, which is not copyable and for which you can not specify a deleter. std::unique_pt...
构建高并发高可用的电商平台架构实践 - 更多技术 - 清泛网 - 专注C/C++及内核技术
...，包括leader选举等等，保障集群的可用性。
Lucene索引的Reader是基于索引的snapshot的，所以必须在索引commit的后，重新打开一个新的snapshot，才能搜索到新添加的内容；而索引的commit是非常耗性能的，这样达到实时索引搜索效率就...
How to create a memory leak in Java?
...stored in memory) in pure Java:
The application creates a long-running thread (or use a thread pool to leak even faster).
The thread loads a class via an (optionally custom) ClassLoader.
The class allocates a large chunk of memory (e.g. new byte[1000000]), stores a strong reference to it in a stat...
Quickly find whether a value is present in a C array?
...de, the compiler will have a hard time hiding the delays because the value read from memory must be immediately compared. My code below alternates between 2 sets of 4 registers to significantly reduce the delays of the memory itself and the pipeline fetching the data. In general, when working with l...