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What is the best regular expression to check if a string is a valid URL?
...C 3987 (http://www.faqs.org/rfcs/rfc3987.html). These are in PCRE syntax.
For absolute IRIs (internationalized):
/^[a-z](?:[-a-z0-9\+\.])*:(?:\/\/(?:(?:%[0-9a-f][0-9a-f]|[-a-z0-9\._~\x{A0}-\x{D7FF}\x{F900}-\x{FDCF}\x{FDF0}-\x{FFEF}\x{10000}-\x{1FFFD}\x{20000}-\x{2FFFD}\x{30000}-\x{3FFFD}\x{40000}-...
Combining C++ and C - how does #ifdef __cplusplus work?
...s that can't be built with C linkage. That means no classes or templates, for example.
extern "C" blocks nest nicely. There's also extern "C++" if you find yourself hopelessly trapped inside of extern "C" regions, but it isn't such a good idea from a cleanliness perspective.
Now, specifically re...
Should you always favor xrange() over range()?
...
For performance, especially when you're iterating over a large range, xrange() is usually better. However, there are still a few cases why you might prefer range():
In python 3, range() does what xrange() used to do and xr...
Why can't I overload constructors in PHP?
...tions of parameters, use the factory pattern with a private constructor.
For example:
public MyClass {
private function __construct() {
...
}
public static function makeNewWithParameterA($paramA) {
$obj = new MyClass();
// other initialization
return $obj...
What does the restrict keyword mean in C++?
...ny C++ compilers
! A hint only, so may do nothing and still be conforming
A restrict-qualified pointer (or reference)...
! ...is basically a
promise to the compiler that for the
scope of the pointer, the target of the pointer will only
be accessed through that ...
What is the difference between quiet NaN and signaling NaN?
...ented in software. A signalling NaN will produce a signal, usually in the form of exception from the FPU. Whether the exception is thrown depends on the state of the FPU.
C++11 adds a few language controls over the floating-point environment and provides standardized ways to create and test for N...
How to convert list of tuples to multiple lists?
...
franklsf95 goes for performance in his answer and opts for list.append(), but they are not optimal.
Adding list comprehensions, I ended up with the following:
def t1(zs):
xs, ys = zip(*zs)
return xs, ys
def t2(zs):
xs, ys = []...
Get event listeners attached to node using addEventListener
...
Any chance of supplying some justification or reasoning for why it must work this way? Clearly the browser knows what all of the listeners are.
– Darth Egregious
Apr 5 '12 at 19:23
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Is there a performance difference between a for loop and a for-each loop?
What, if any, is the performance difference between the following two loops?
16 Answers
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In Python, how do I indicate I'm overriding a method?
In Java, for example, the @Override annotation not only provides compile-time checking of an override but makes for excellent self-documenting code.
...