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Why do we need C Unions?
...
Unions are often used to convert between the binary representations of integers and floats:
union
{
int i;
float f;
} u;
// Convert floating-point bits to integer:
u.f = 3.14159f;
printf("As integer: %08x\n", u.i);
Although this ...
What does the “at” (@) symbol do in Python?
...symbol, but I have no idea what it does. I also do not know what to search for as searching Python docs or Google does not return relevant results when the @ symbol is included.
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find -exec with multiple commands
I am trying to use find -exec with multiple commands without any success. Does anybody know if commands such as the following are possible?
...
How to grant permission to users for a directory using command line in Windows?
...s instead. This is how you grant John full control over D:\test folder and all its subfolders:
C:\>icacls "D:\test" /grant John:(OI)(CI)F /T
According do MS documentation:
F = Full Control
CI = Container Inherit - This flag indicates that subordinate containers will inherit this ACE.
OI = Ob...
What is a regular expression for a MAC Address?
...at" comes from Wikipedia, not the 802.3 standards body. IEEE 802-2014 actually specifies hyphens for ordinary MAC addresses (§ 8.1 ¶ 3) and colons for the obsolescent bit-reversed notation (¶ 4). Importantly, in practice, no one observes this. We simply use one or the other, but never mix them...
How to paste yanked text into the Vim command line
...you know how to use them you cannot live without them.
Registers are basically storage locations for strings. Vim has many registers that work in different ways:
0 (yank register: when you use y in normal mode, without specifying a register, yanked text goes there and also to the default register...
How to find if a given key exists in a C++ std::map
...a particular key exists."
The documentation for map::count says: "Because all elements in a map container are unique, the function can only return 1 (if the element is found) or zero (otherwise)."
To retrieve a value from the map via a key that you know to exist, use map::at:
value = m.at(key)
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Objective-C 2.0 Mac和iOS开发实践指南 PDF扫描版 - 文档下载 - 清泛网 - ...
Objective-C 2.0 Mac和iOS开发实践指南 PDF扫描版Objective-C Mac iOS《Objective-C 2.0 Mac和iOS开发实践指南》专门为那些想要学习Objecti Ve-C以便为Mac OS x或iOS编写程序的程序员量身打造。《Objectiv...截图：
《Objective-C 2.0 Mac和iOS开发实践指南...
Haskell composition (.) vs F#'s pipe forward operator (|>)
...s pipelining, so that a known type appears on the left (see here).
(Personally, I find points-free style unreadable, but I suppose every new/different thing seems unreadable until you become accustomed to it.)
I think both are potentially viable in either language, and history/culture/accident may...
Understanding the Rails Authenticity Token
...ares it to the one stored in the session, and if they match the request is allowed to continue.
Why it happens
Since the authenticity token is stored in the session, the client cannot know its value. This prevents people from submitting forms to a Rails app without viewing the form within that app...