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Covariance and contravariance real world example
...);
Covariant(fruit);
Covariant(apple); //apple is being upcasted to fruit, without the out keyword this will not compile
}
public void Contravariance()
{
IContravariant<Fruit> fruit = new Contravariant<Fruit>();
IContravariant<Apple> ap...
Difference between “!==” and “==!” [closed]
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false because "a" is not equals to !" " !" " means cast to bool and negate that so " " is true and !" " is false.
– Zaffy
Sep 8 '12 at 13:07
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How do I enumerate through a JObject?
...asons I don't understand, you can't use it with Linq unless you explicitly cast to the enumerable type. I.e. you ((IEnumerable<KeyValuePair<string, JToken>>)obj).Select(...) instead of plain-old obj.Select(...); or at least that's what I found it one part of my code.
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Efficiently convert rows to columns in sql server
... + 'SELECT ''INSERT INTO @ColumnListWithActions VALUES ('' + CAST( ROW_NUMBER() OVER (ORDER BY [NAME]) as nvarchar(10)) + '', '' + '''''''' + [NAME] + ''''''''+ '', ''''S'''');'''
+ 'FROM [' + @DB_Name + '].sys.columns '
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SQL Data Reader - handling Null column values
...sqlreader[indexAge] as int? ?? default(int);
The as operator handles the casting including the check for DBNull.
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Does MS SQL Server's “between” include the range boundaries?
... When using BETWEEN to filter DateTimes between two dates, you can also cast the DateTime to a Date, eg: where CONVERT(DATE, MyDate) BETWEEN '2017-09-01' and '2017-09-30' This approach makes the time element of the DateTime irrelevant
– Pete
Sep 15 '17 at 9...
C++11 emplace_back on vector?
...he member, the argument is treated as an lvalue again, in the absence of a cast, so the member just gets copy-constructed. Even if the member was move-constructed, it's not idiomatic to require callers always to pass a temporary or std::move()d lvalue (though I will confess that I have a few corner-...
How to convert An NSInteger to an int?
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I get a warning using the suggested "casting": Implicit conversion loses integer precision: 'NSUInteger' (aka 'unsigned long') to 'int'
– djcj
Sep 18 '14 at 16:52
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Why no generics in Go?
...ject or Objective-C's id types. Type information is preserved and can be "cast" (asserted, actually) back to its concrete type. Get the gritty details here: golang.org/ref/spec#Type_assertions
– tbone
Aug 25 '13 at 20:50
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How to use performSelector:withObject:afterDelay: with primitive types in Cocoa?
...trick if it is a BOOL parameter.
Pass nil for NO and self for YES. nil is cast to the BOOL value of NO. self is cast to the BOOL value of YES.
This approach breaks down if it is anything other than a BOOL parameter.
Assuming self is a UIView.
//nil will be cast to NO when the selector is perform...