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Programmatically find the number of cores on a machine
...<thread>
//may return 0 when not able to detect
const auto processor_count = std::thread::hardware_concurrency();
Reference: std::thread::hardware_concurrency
In C++ prior to C++11, there's no portable way. Instead, you'll need to use one or more of the following methods (guarded by app...
What's the difference between lists and tuples?
...e 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 list on the other hand could be used to store multiple locations. Naturally one might want to ad...
Iterate over the lines of a string
...< 0: break
yield foo[prevnl + 1:nextnl]
prevnl = nextnl
if __name__ == '__main__':
for f in f1, f2, f3:
print list(f())
Running this as the main script confirms the three functions are equivalent. With timeit (and a * 100 for foo to get substantial strings for more precise me...
Preloading images with JavaScript
...OP:
var preloadImage = function (url) {
try {
var _img = new Image();
_img.src = url;
} catch (e) { }
}
Standard:
function preloadImage (url) {
try {
var _img = new Image();
_img.src = url;
} catch (e) { ...
What characters are valid for JavaScript variable names?
...mmarizing the relevant spec sections:
An identifier must start with $, _, or any character in the Unicode categories “Uppercase letter (Lu)”, “Lowercase letter (Ll)”, “Titlecase letter (Lt)”, “Modifier letter (Lm)”, “Other letter (Lo)”, or “Letter number (Nl)”.
The r...
What is a regular expression for a MAC Address?
...perty \p{xdigit} includes the FULLWIDTH versions. You might prefer \p{ASCII_Hex_Digit} instead.
The answer to the question asked might be best answered — provided you have a certain venerable CPAN module installed — by typing:
% perl -MRegexp::Common -lE 'say $RE{net}{MAC}'
I show the partic...
Extract file name from path, no matter what the os/path format
...asename will be empty, so make your own function to deal with it:
def path_leaf(path):
head, tail = ntpath.split(path)
return tail or ntpath.basename(head)
Verification:
>>> paths = ['a/b/c/', 'a/b/c', '\\a\\b\\c', '\\a\\b\\c\\', 'a\\b\\c',
... 'a/b/../../a/b/c/', 'a/b/../....
Trying to mock datetime.date.today(), but not working
...ock.patch('datetime.date.today')
def test():
datetime.date.today.return_value = date(2010, 1, 1)
print datetime.date.today()
Unfortunately, this won't work:
>>> test()
Traceback (most recent call last):
File "<stdin>", line 1, in <module>
File "build/bdist.macosx-...
PDO closing connection
...>connection = new PDO();
$this->connection->query('KILL CONNECTION_ID()');
$this->connection = null;
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Code Golf - π day
...
Perl, 95 96 99 106 109 110 119 characters:
$t+=$;=1|2*sqrt($r**2-($u-2*$_)**2),say$"x($r-$;/2).'*'x$;for 0..
($u=($r=<>)-1|1);say$t*2/$r**2
(The newline can be removed and is only there to avoid a scrollbar)
Yay! Circle version!
$t+=$;=
1|2*sqrt($r**
2-($u-2*$_)**2)
,say$"x($r-$;/2
)....