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Performance surprise with “as” and nullable types
...d is of the expected type, takes but a few machine code instructions. The cast is also easy, the JIT compiler knows the location of the value bits in the object and uses them directly. No copying or conversion occurs, all machine code is inline and takes but about a dozen instructions. This neede...
How to loop through all enum values in C#? [duplicate]
...Foos));
Or the typed version:
var values = Enum.GetValues(typeof(Foos)).Cast<Foos>();
I long ago added a helper function to my private library for just such an occasion:
public static class EnumUtil {
public static IEnumerable<T> GetValues<T>() {
return Enum.GetVa...
Store select query's output in one array in postgres
...
There are two ways. One is to aggregate:
SELECT array_agg(column_name::TEXT)
FROM information.schema.columns
WHERE table_name = 'aean'
The other is to use an array constructor:
SELECT ARRAY(
SELECT column_name
FROM information.schema.columns
WHERE table_name = ...
How to avoid the “divide by zero” error in SQL?
...rder to avoid a "Division by zero" error we have programmed it like this:
Select Case when divisor=0 then null
Else dividend / divisor
End ,,,
But here is a much nicer way of doing it:
Select dividend / NULLIF(divisor, 0) ...
Now the only problem is to remember the NullIf bit, if I use the "/"...
Ignore Typescript Errors “property does not exist on value of type”
...erHtmlElement.getBBox();
###Edit, late 2016
Since TypeScript 1.6 prefered casting operator is as those lines can be squashed into:
let coordinates = (outerElement[0] as any).getBBox();
###Other solutions
Of course if you'd like to do it right, which is an overkill sometimes, you can:
Create own i...
How does std::forward work? [duplicate]
...does according to the standard:
§20.2.3 [forward] p2
Returns: static_cast<T&&>(t)
(Where T is the explicitly specified template parameter and t is the passed argument.)
Now remember the reference collapsing rules:
TR R
T& & -> T& // lvalue reference to c...
iOS: How to store username/password within an app?
... 3 right-click on frameworks folder and add existing framework. In Xcode 4 select your project, then select target, go to Build Phases tab and click + under Link Binary With Files) and KeychainItemWrapper .h & .m files into your project, #import the .h file wherever you need to use keychain and ...
Converting an int to std::string
...
boost::lexical_cast<std::string>(yourint) from boost/lexical_cast.hpp
Work's for everything with std::ostream support, but is not as fast as, for example, itoa
It even appears to be faster than stringstream or scanf:
http://www....
Sorting an IList in C#
...rty, I believe you could sort as follows:
from c in list
orderby c.Engine
select c;
Edit: You do need to be quick to get answers in here. As I presented a slightly different syntax to the other answers, I will leave my answer - however, the other answers presented are equally valid.
...
C++ equivalent of java's instanceof
...
Try using:
if(NewType* v = dynamic_cast<NewType*>(old)) {
// old was safely casted to NewType
v->doSomething();
}
This requires your compiler to have rtti support enabled.
EDIT:
I've had some good comments on this answer!
Every time you need...