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How are strings passed in .NET?
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A reference is passed; however, it's not technically passed by reference. This is a subtle, but very important distinction. Consider the following code:
void DoSomething(string strLocal)
{
strLocal = "local";
}
void Main()
{
string strMain = "main";
DoSomething(strMain);
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How to return smart pointers (shared_ptr), by reference or by value?
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Return smart pointers by value.
As you've said, if you return it by reference, you won't properly increment the reference count, which opens up the risk of deleting something at the improper time. That alone should be enough reason to not return ...
@Resource vs @Autowired
...th, without specifying any attributes of the annotation, perform injection by type. The difference is:
@Resource allows you to specify a name of the injected bean
@Autowired allows you to mark it as non-mandatory.
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Test if element is present using Selenium WebDriver?
...nt is present, you could try this
Boolean isPresent = driver.findElements(By.yourLocator).size() > 0
This will return true if at least one element is found and false if it does not exist.
The official documentation recommends this method:
findElement should not be used to look for non-pre...
Mean per group in a data.frame [duplicate]
...667 54.00000
Here we aggregate columns 3 and 4 of data.frame d, grouping by d$Name, and applying the mean function.
Or, using a formula interface:
aggregate(. ~ Name, d[-2], mean)
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Why does C++11's lambda require “mutable” keyword for capture-by-value, by default?
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It requires mutable because by default, a function object should produce the same result every time it's called. This is the difference between an object orientated function and a function using a global variable, effectively.
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How do I limit the number of rows returned by an Oracle query after ordering?
... the original question, here's the query:
SELECT *
FROM sometable
ORDER BY name
OFFSET 20 ROWS FETCH NEXT 10 ROWS ONLY;
(For earlier Oracle versions, please refer to other answers in this question)
Examples:
Following examples were quoted from linked page, in the hope of preventing link rot.
Se...
find() with nil when there are no records
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Yes, just do:
Challenge.find_by_id(10)
For Rails 4 and 5:
Challenge.find_by(id: 10)
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Understanding the ngRepeat 'track by' expression
I'm having difficulties understanding how the track by expression of ng-repeat in angularjs works. The documentation is very scarce: http://docs.angularjs.org/api/ng/directive/ngRepeat
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ORDER BY the IN value list
... (3,2),
(2,3),
(4,4)
) as x (id, ordering) on c.id = x.id
order by x.ordering
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