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Update MongoDB field using value of another field
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The best way to do this is in version 4.2+ which allows using of aggregation pipeline in the update document and the updateOne, updateMany or update collection method. Note that the latter has been deprecated in most if not all languages drivers.
MongoDB 4.2+
Version 4.2 ...
How to count the number of set bits in a 32-bit integer?
...Hamming Weight', 'popcount' or 'sideways addition'.
The 'best' algorithm really depends on which CPU you are on and what your usage pattern is.
Some CPUs have a single built-in instruction to do it and others have parallel instructions which act on bit vectors. The parallel instructions (like x86's ...
How to split a string in Java
... bracket [, the opening curly brace {, These special characters are often called "metacharacters".
So, if you want to split on e.g. period/dot . which means "any character" in regex, use either backslash \ to escape the individual special character like so split("\\."), or use character class [] t...
UITextView that expands to text using auto layout
I have a view that is laid out completely using auto layout programmatically. I have a UITextView in the middle of the view with items above and below it. Everything works fine, but I want to be able to expand UITextView as text is added. This should push everything below it down as it expands.
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Is “else if” a single keyword?
...er to Can you start a class name with a numeric digit? that spaces are not allowed in identifiers and so therefore else if can not be a single keyword but must be two separate keywords.
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Getting MAC Address
... says that it will return a random long if it fails to detect the mac: "If all attempts to obtain the hardware address fail, we choose a random 48-bit number with its eighth bit set to 1 as recommended in RFC 4122." So check that eighth bit!
– deinonychusaur
Fe...
Can “list_display” in a Django ModelAdmin display attributes of ForeignKey fields?
...e that is what the string you're returning (and the short description) actually reference? Or change string format argument to obj.book.reviews?
– Carl G
Jun 20 '12 at 19:12
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Remove file extension from a file name string
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Watch out for files with no extension, like foo/bar.cat/cheese!
– Cameron
Jan 24 '14 at 14:54
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What does “program to interfaces, not implementations” mean?
...t worried about implementation and the interface signature determines what all operations can be done. This can be used to change the behavior of a program at run-time. It also helps you to write far better programs from the maintenance point of view.
Here's a basic example for you.
public enum La...
Stop all active ajax requests in jQuery
I have a problem, when submitting a form all active ajax request fail, and that triggers error event.
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