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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 ...
What's the difference between __PRETTY_FUNCTION__, __FUNCTION__, __func__?
... = "function-name";
appeared, where function-name is the name of the lexically-enclosing function. This name is the unadorned name of the function.
Note that it is not a macro and it has no special meaning during preprocessing.
__func__ was added to C++ in C++11, where it is specified as containi...
When is the init() function run?
...The = 0
}
func main() {
if WhatIsThe == 0 {
fmt.Println("It's all a lie.")
}
}
AnswerToLife() is guaranteed to run before init() is called, and init() is guaranteed to run before main() is called.
Keep in mind that init() is always called, regardless if there's main or not, so if...
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 ...
Xcode 4.5 Storyboard 'Exit'
I have just installed Xcode 4.5 for iOS6 support, and I have seen a new icon called 'Exit' in my Storyboard, listed under my view controllers along with 'First Responder' etc. A little green icon labeled 'Exit'.
...
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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impr...
Rename multiple files in a directory in Python [duplicate]
...e script itself. Instead of using . as the dir, you could make a variable called dir and use that, then prepend dir to the filename.
– styfle
May 18 '11 at 5:53
18
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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.
16 Answers
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What's the fastest way to loop through an array in JavaScript?
...o
Currently, the fastest form of loop (and in my opinion the most syntactically obvious).
A standard for-loop with length caching
var i = 0, len = myArray.length;
while (i < len) {
// your code
i++
}
I would say, this is definitely a case where I applaud JavaScript en...
Good tutorials on XMPP? [closed]
...Library from Ignite Realtime and used the groovy language with a buch of small scripts to learn the basics.
Later i developed a plugin for the OpenFire XMPP Server. There are some tutorials and a forum on their site as well. I think that both the smack and the openfire api's are easy to learn.
I...