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Why is XOR the default way to combine hashes?
Say you have two hashes H(A) and H(B) and you want to combine them. I've read that a good way to combine two hashes is to XOR them, e.g. XOR( H(A), H(B) ) .
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Is it possible to set a number to NaN or infinity?
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On python >= 2.6, you can just use math.isnan() and math.isinf()
– Agos
May 9 '11 at 10:21
10
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MYSQL OR vs IN performance
... not believe people who give their "opinion", science is all about testing and evidence.
I ran a loop of 1000x the equivalent queries (for consistency, I used sql_no_cache):
IN: 2.34969592094s
OR: 5.83781504631s
Update:
(I don't have the source code for the original test, as it was 6 years ago, ...
Is short-circuiting logical operators mandated? And evaluation order?
Does the ANSI standard mandate the logical operators to be short-circuited, in either C or C++?
7 Answers
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Set every cell in matrix to 0 if that row or column contains a 0
Given a NxN matrix with 0s and 1s. Set every row that contains a 0 to all 0 s and set every column that contains a 0 to all 0 s.
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How to check iOS version?
...lable(iOS 9, *) {}
In Objective-C, you need to check the system version and perform a comparison.
[[NSProcessInfo processInfo] operatingSystemVersion] in iOS 8 and above.
As of Xcode 9:
if (@available(iOS 9, *)) {}
The full answer …
In Objective-C, and Swift in rare cases, it's better to...
Accessing class variables from a list comprehension in the class definition
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Class scope and list, set or dictionary comprehensions, as well as generator expressions do not mix.
The why; or, the official word on this
In Python 3, list comprehensions were given a proper scope (local namespace) of their own, to p...
Cookies on localhost with explicit domain
...sic thing about cookies. On localhost, when I set a cookie on server side and specify the domain explicitly as localhost (or .localhost). the cookie does not seem to be accepted by some browsers.
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IF… OR IF… in a windows batch file
...lternative is to use an indicator variable. Initialize it to be undefined, and then define it only if any one of the OR conditions is true. Then use IF DEFINED as a final test - no need to use delayed expansion.
FOR ..... DO (
set "TRUE="
IF cond1 set TRUE=1
IF cond2 set TRUE=1
IF defined TR...
Database sharding vs partitioning
...two words that keep on showing up with regards to databases are sharding and partitioning . I looked up descriptions but still ended up confused.
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