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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...
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...
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...
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 ...
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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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...
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...