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In C#, should I use string.Empty or String.Empty or “” to intitialize a string?
...erence is negligible - massively, massively insignificant.
Which you find more readable is a different matter, however. It's subjective and will vary from person to person - so I suggest you find out what most people on your team like, and all go with that for consistency. Personally I find "" easi...
Caveats of select/poll vs. epoll reactors in Twisted
...that's roughly twice as expensive as selecting on a single fd, 50. Adding more fds below the highest isn't quite free, so it's a little more complicated than this in practice, but this is a good first approximation for most implementations.
The cost of epoll is closer to the number of file descrip...
What is this crazy C++11 syntax ==> struct : bar {} foo {};?
...finition
struct foo { foo() { cout << "!"; } } instance; // so much more
// Output: "!"
Let's combine the examples, and recall that we can define a UDT that has no name:
struct { virtual void f() = 0; } instance; // unnamed abstract type
// error: cannot declare variable 'instance' to be o...
Weird PHP error: 'Can't use function return value in write context'
...empty($someVar)
Wrong:
empty(someFunc())
Since PHP 5.5, it supports more than variables. But if you need it before 5.5, use trim($name) == false. From empty documentation.
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Reverse / invert a dictionary mapping
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Volatile vs Static in Java
...cessor or core. See cs.umd.edu/~pugh/java/memoryModel/jsr-133-faq.html for more details.
– stivlo
Dec 17 '12 at 22:08
15
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what exactly is device pixel ratio?
... in CSS always operates on logical pixels.
A case for vector graphics
As more and more device types appear, it gets trickier to provide all of them with adequate bitmap resources. In CSS, media queries is currently the only way, and in HTML5, the picture element lets you use different sources for ...
Change column type from string to float in Pandas
...supports pd.NA (pandas' object to indicate a missing value).
Read on for more detailed explanations and usage of each of these methods.
1. to_numeric()
The best way to convert one or more columns of a DataFrame to numeric values is to use pandas.to_numeric().
This function will try to change non-...
How do I apply the for-each loop to every character in a String?
... to contain the character sequence represented by this string.
There are more verbose ways of iterating over characters in an array (regular for loop, CharacterIterator, etc) but if you're willing to pay the cost toCharArray() for-each is the most concise.
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Find size of Git repository
...
UPDATE git 1.8.3 introduced a more efficient way to get a rough size: git count-objects -vH (see answer by @VonC)
For different ideas of "complete size" you could use:
git bundle create tmp.bundle --all
du -sh tmp.bundle
Close (but not exact:)
git g...