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“for” vs “each” in Ruby
...The reason why x remains in the for scenario is due to the fact that (generally speaking) keywords don't create new scopes. if, unless, begin, for, while, etc. all work with the current scope. #each however accepts a block. Blocks always add their own scope on top of the current scope. Meaning that ...
Allowed characters in Linux environment variable names
What characters are allowed in Linux environment variable names? My cursory search of man pages and the web did only produce information about how to work with variables, but not which names are allowed.
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What exactly does big Ө notation represent?
I'm really confused about the differences between big O, big Omega, and big Theta notation.
6 Answers
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What is more efficient: Dictionary TryGetValue or ContainsKey+Item?
...ll be faster.
ContainsKey uses the same check as TryGetValue, which internally refers to the actual entry location. The Item property actually has nearly identical code functionality as TryGetValue, except that it will throw an exception instead of returning false.
Using ContainsKey followed by t...
Do I set properties to nil in dealloc when using ARC?
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Short answer: no, you do not have to nil out properties in dealloc under ARC.
Long answer: You should never nil out properties in dealloc, even in manual memory management.
In MRR, you should release your ivars. Nilling out properties means calling setters, which may invoke code that...
What is the _references.js used for?
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In VS 11, Visual Studio will give you intellisense from all files
that have references in the “_references.js” file.
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How do I concatenate two arrays in C#?
...ays. It seems the only functional purpose for using arrays is for Interop calls (Unmanaged C++).
– Levi Fuller
Oct 26 '15 at 22:40
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arrayfun can be significantly slower than an explicit loop in matlab. Why?
...lution is clearly the fastest, you can see that defining a function to be called for every x entry is a huge overhead. Just explicitly writing out the computation got us factor 5 speedup. I guess this shows that MATLABs JIT compiler does not support inline functions. According to the answer by gnovi...
Rename MySQL database [duplicate]
...atabase with the database name you wanted.
The short, quick steps without all the above explanation are:
mysqldump -u root -p original_database > original_database.sql
mysql -u root -p -e "create database my_new_database"
mysql -u root -p my_new_database < original_database.sql
mysql -u roo...
SQL Update with row_number()
...able and made the CTE look as if it was a recursive CTE, because it essentially referenced itself. A recursive CTE must have a specific structure which requires the use of the UNION ALL set operator.
Instead, you could just have given the CTE a different name as well as added the target column to i...