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What is a non-capturing group in regular expressions?
...to explain this with an example.
Consider the following text:
http://stackoverflow.com/
https://stackoverflow.com/questions/tagged/regex
Now, if I apply the regex below over it...
(https?|ftp)://([^/\r\n]+)(/[^\r\n]*)?
... I would get the following result:
Match "http://stackoverflow.com/"
...
JavaScript error (Uncaught SyntaxError: Unexpected end of input)
I have some JavaScript code that works in FireFox but not in Chrome or IE.
10 Answers
...
Why is using “for…in” for array iteration a bad idea?
...
5
*/
Also consider that JavaScript libraries might do things like this, which will affect any array you create:
// Somewhere deep in your JavaScript library...
Array.prototype.foo = 1;
// Now you have no idea what the below code will do.
var a = [1, 2, 3, 4, 5];
for (var x in ...
PHP 5: const vs static
...s, static variables are on the class scope (not the object) scope, but unlike a const, their values can be changed.
class ClassName {
static $my_var = 10; /* defaults to public unless otherwise specified */
const MY_CONST = 5;
}
echo ClassName::$my_var; // returns 10
echo ClassName::MY_C...
How to set HTTP headers (for cache-control)?
...or my site? Do I just put cache-control:public somewhere up in my header like this?
8 Answers
...
Big O of JavaScript arrays
...cript are very easy to modify by adding and removing items. It somewhat masks the fact that most languages arrays are fixed-size, and require complex operations to resize. It seems that JavaScript makes it easy to write poorly performing array code. This leads to the question:
...
Are HLists nothing more than a convoluted way of writing tuples?
...ations for HLists is abstracting over arity. Arity is typically statically known at any given use site of an abstraction, but varies from site to site. Take this, from shapeless's examples,
def flatten[T <: Product, L <: HList](t : T)
(implicit hl : HListerAux[T, L], flatten : Flatten[L]) :...
Find method references in Xcode
...top-left of the Editor. (It's the button immediately to the left of the back button).
Go to the "Callers" submenu for a list of all methods that call the selected method, and click any of them to jump to that file and method.
In pictures...
A couple of notes:
You can do this for properties ...
Null coalescing in powershell
...forms.
You might also consider wrapping it in a very simple function to make things more readable:
function Coalesce($a, $b) { if ($a -ne $null) { $a } else { $b } }
$s = Coalesce $myval "new value"
or possibly as, IfNull:
function IfNull($a, $b, $c) { if ($a -eq $null) { $b } else { $c } }
$...
Count with IF condition in MySQL query
... Or even SUM(ccc_news_comments.id = 'approved') as a MySQL-specific trick
– mojuba
Jan 21 '13 at 20:44
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