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Python extract pattern matches
...h a standard python REPL, the last result is stored in a special variable called _. It isn't valid outside anywhere else.
– UltraInstinct
Mar 13 '19 at 2:25
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Retrieve only the queried element in an object array in MongoDB collection
...r to filter an array during projection, which has the benefit of including all matches, instead of just the first one.
db.test.aggregate([
// Get just the docs that contain a shapes element where color is 'red'
{$match: {'shapes.color': 'red'}},
{$project: {
shapes: {$filter: {
...
Two submit buttons in one form
...
Normally, all inputs in the form are sent with the form. Since a button's value is submitted only if clicked, you'd have to search the form values for these pre-defined names. I think the other answer (stackoverflow.com/a/21778...
Why use sprintf function in PHP?
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sprintf has all the formatting capabilities of the original printf which means you can do much more than just inserting variable values in strings.
For instance, specify number format (hex, decimal, octal), number of decimals, padding a...
Is gettimeofday() guaranteed to be of microsecond resolution?
I am porting a game, that was originally written for the Win32 API, to Linux (well, porting the OS X port of the Win32 port to Linux).
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PHP abstract properties
...get_class($this) . ' must have a $tablename');
}
}
To enforce this for all derived classes of Foo_Abstract you would have to make Foo_Abstract's constructor final, preventing overriding.
You could declare an abstract getter instead:
abstract class Foo_Abstract {
abstract public function get_...
What is the difference between Θ(n) and O(n)?
...e of the algorithm as n gets larger is at most proportional to g(n).
Normally, even when people talk about O(g(n)) they actually mean Θ(g(n)) but technically, there is a difference.
More technically:
O(n) represents upper bound. Θ(n) means tight bound.
Ω(n) represents lower bound.
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How to concatenate twice with the C preprocessor and expand a macro as in “arg ## _ ## MACRO”?
...ssing token (see below), is
replaced by the corresponding argument after all macros contained therein have been
expanded. Before being substituted, each argument’s preprocessing tokens are
completely macro replaced as if they formed the rest of the preprocessing file; no other
preprocessin...
How do you round a floating point number in Perl?
.... For rounding to a certain number of digits, sprintf() or printf() is usually the easiest
route.
printf("%.3f", 3.1415926535); # prints 3.142
The POSIX module (part of the standard Perl distribution) implements
ceil(), floor(), and a number of other mathematical and trigonometric
func...
How do I localize the jQuery UI Datepicker?
I really need a localized dropdown calendar. An English calendar doesn't exactly communicate excellence on a Norwegian website ;-)
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