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Random record from MongoDB
...from a collection using the $sample aggregation pipeline operator:
// Get one random document from the mycoll collection.
db.mycoll.aggregate([{ $sample: { size: 1 } }])
If you want to select the random document(s) from a filtered subset of the collection, prepend a $match stage to the pipeline:
...
Thread pooling in C++11
...hreads are created according to Num_Threads, it's better not to create new ones, or destroy old ones (by joining). There will be performance penalty, might even make your application goes slower than the serial version.
Each C++11 thread should be running in their function with an infinite loop, co...
Definition of a Balanced Tree
I am just wondering if someone might be able to clarify the definition of a balanced tree for me. I have that "a tree is balanced if each sub-tree is balanced and the height of the two sub-trees differ by at most one.
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Difference between int32, int, int32_t, int8 and int8_t
...ze can vary (in terms of number of bits) but it's guaranteed to be exactly one byte. One slight oddity though: there's no guarantee about whether a plain char is signed or unsigned (and many compilers can make it either one, depending on a compile-time flag). If you need to ensure its being either s...
Thou shalt not inherit from std::vector
...re using it. What's the difference between std::vector and MyVector? Which one is better to use here and there? What if I need to move std::vector to MyVector? May I just use swap() or not?
Do not produce new entities just to make something to look better. These entities (especially, such common) a...
parseInt vs unary plus, when to use which?
...aracter, it returns what has been parsed (if any) as a number, and NaN if none was parsed as a number.
The unary + on the other hand will return NaN if the entire string is non-convertible to a number.
parseInt('2a',10) === 2; //true
parseFloat('2a') === 2; //true
isNaN(+'2a'); //t...
using href links inside tag
... to have a drop menu there are plenty of arguably better ways to implement one. This answer is a direct answer to a direct question, but I don't advocate this method for public facing web sites.
UPDATE (May 2020): Someone asked in the comments why I wouldn't advocate this solution. I guess it's a q...
How to change column order in a table using sql query in sql server 2005?
... Both obviously not recommended practices, but SQL Server allows it so someone may have used it somewhere, possibly breaking T-SQL code when changing column order.
– Carvellis
Jul 7 '14 at 13:38
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How can I add some small utility functions to my AngularJS application?
...to point out that a couple of the point @nicolas makes below are good. For one, injecting $rootScope and attaching the helpers there will keep you from having to add them for every controller. Also - I agree that if what you're adding should be thought of as Angular services OR filters, they should ...
What's the difference between lists and tuples?
...er.
Using this distinction makes code more explicit and understandable.
One example would be pairs of page and line number to reference locations in a book, e.g.:
my_location = (42, 11) # page number, line number
You can then use this as a key in a dictionary to store notes on locations. A li...